Rewind: Trailer

I've finally got round to uploading my 'Rewind' video trailer to YouTube.

I didn't have time to complete the working level I'd intended, so I put together an animatic to demonstrate the intended operation of the game environment, demonstrating key features.

It was a tight squeeze completing it for the final deadline, but I'm happy with the overall result.

MA Show

In this MA I have sought to demonstrate that nostalgia can add value to video games.

Through practice-led research I have experimented with a range of aesthetic & mechanical elements, backed-up by literature research and study into ludology and associated topics.

Nostalgia can arouse intense emotions; it is frequently invoked in film, television, retail & advertising.

However, its application in gaming is minimal — chiefly confined to ‘retro’ referencing of older video games.

The aim of ‘Rewind’ is to demonstrate the potential for broader application of nostalgia in game design by employing targeted ‘triggers’ to build a virtual world that can engage players both creatively and emotionally.

I believe that this has been demonstrated, and that the work I have done will contribute to a greater body of work among my peers.

In addition, through my employment as a college lecturer, I am already disseminating many of the philosophies, theories and skills gained during this process.  My game models are used as demonstration pieces to show particular techniques; my blogs are used to pull examples "out-of-a-hat" when provoking discussion on gender in gaming; my case studies are used to illustrate the overall development process.

The Rewind game is only part-built -- no small feat for a one-person studio with very limited spare time, but it embodies the philosophy I have evolved over the last 25 months:

This research explores the potential of nostalgic ‘triggers’ as a tool in the development of aesthetic & mechanical game elements.

Such triggers can be identified via collections of historical ephemera, which provide a rich source of ideas.

As part of this process, techniques have been established to adjust the emotional impact of these triggers by analytical classification and selective combination.

These techniques are augmented by the use of background semiotic cues — employing colour, light and styling to imply time period and social context.

The “Rewind” game design contains applied use of these triggers, techniques and semiotic cues in a single proof-of-concept product.

 

The conclusion of this study is that nostalgia may be applied successfully to aesthetic & mechanical video game design elements in order to add value in the form of emotional affect.

The end of my MA Journey

It's just over two years since I began this MA journey and I think it's fair to say that it's changed my life.

Not just in terms of extending myself academically, gaining a qualification, gaining new understanding or learning new skills.  It has set me down a new path.  Earlier this summer I set up Strontium Games, my own game development studio.

One of the most important things about having a games company is, of course, having a snazzy logo:

It may look like only a small thing but it's a major step for a mature student like myself.  I intend to continue designing and developing games; researching, learning, reflecting & reflecting as I gain greater mastery of the discipline.  And that, to me, is what a Master's Degree is all about.

Rewind: 1980s room

I've already written quite a bit about the 1980s room I created for my "Gizmo" project, including some of the accompanying nostalgia trigger items.  For Rewind, I rearranged & adapted this room, reusing many of the objects within.

Extra models and details were added, including:

• More LPs and cassettes
• An out-of-box cassette, with unspooled tape
• Portable cassette recorder
• WHSmith pencil (for winding back said tape!)
• ZX81 home computer
• Rubik's Barrel toy
• Rubik's Snake toy
• British Telecom phonecard

For the purpose of the final video simulation, shadows were added from the renderer.  They look pretty bad, but that's a limitation of the depth map shadowing I was using.  Shadows are important for this room so the finished game would use fake planar shadows (on alpha channels) mixed with baked shadows on fixed objects.

I'm fairly happy with this room as a good example of what the Rewind game is about.  When showing a video clip to a colleague his first reaction was a please exclamation of "I used to have one of those!" (referring to the Galaxy Invader 10000) -- that pretty much embodies the emotional reaction I wanted this to produce.

Rewind: 1970s room

For the 1970s level I decided to do a living room, allowing me to scatter toys and other ephemera freely and also using it as an excuse for some period furniture (such as a G-Plan sideboard).

In the scene above you can see a handful of game objects:

• GPO model 706 phone (in Avocado), with connection block
• Telephone seat
• 1975 phone directory and Yellow Pages
• A can of Top Deck Lemonade Shandy, with ring-pull
• G-plan sideboard
• (Armrest belonging to a) Dralon-upholstered settee
• Raleigh Chopper bicycle

There are also a number of background semiotics to reinforce the 1970s context:

• Predominantly brown-orange-white colour palette
• Luminance shift: black lifted to dark grey
• Period patterned wallpaper
• Dark brown plain carpet
• Net curtains
• Wood-framed windows (with French windows at rear) with opening arm and decorative latch

It's worth noting that most visual references I found balance the carpet and wallpaper: if one was patterned, the other was plain.  Therefore I kept to that principle.

Unfortunately, due to time constraints, I didn't get the chance to make side curtains, which would have been a patterned carmine red colour.  Other intended objects included:

• G-Plan dining table with chairs
• Upright radiogram with stacking spindle on the turntable
• Electric bar fire with plastic fake coal effect top
• Wall clock with star-shaped surround
• Spanish holiday ephemera

Still, what I have produced gives a fair indication of the setting:

The next post will deal with some of the toys in the room.

Rewind: 1970s toys

The 1970s room also contains other objects, such as a "Little Snoopy" wooden pull-toy.  I'm particularly pleased with this model considering how quickly it was produced.  It consists of 600 triangles (a relatively low poly-count for such a detailed model) but I'm sure that it could be optimised further with more time available.  All part of the learning process.

The toy is animated to mimic the motion caused by the lopsided wheels.

Another toy is the Simon electronic game, produced by MB Games.  In this case, to avoid trademark issues, I've renamed it "Malcolm".  In Rewind, players will be able to interact with this as a mini-game.

Finally, the View-Master shows stereoscopic images.  In this case I went with the original branding, not realising that they are still manufactured; as a result, the name will need to change.

The object is interactive in Rewind, with players able to look through the eyepieces to discover clues hidden among pictures.  These clues form the backbone of a treasure-hunt game.

Rewind: Intro

It's a very long time since I last posted to the blog, but I promise you I've been very busy!  The last month has seen me bring everything together for the final submission of my body-of-work, including the production of banners and a video for the Art & Design MA Show at UCLan.

The conclusion of my practice-based research takes the form of a game design, with part-built game objects & environment.  Unfortunately I simply don't have the time to build the entire working game,
so I've created a video simulation using existing game objects & environments.

After a splash screen, the game starts with a main menu allowing the player to choose a decade.

Throughout this project I've actively avoided iconic objects (or, being more precise in my semiotic terminology, indices) like the Space Hopper or Rubik's cube.  They are referenced far too commonly in popular culture and have little nostalgia value in themselves (except when digging deeper, such as re-creating that unique Space Hopper bounce sound or a disassembled cube).  In this case though, I needed something instantly recognisable; something that would unambiguously scream "1970s" or "1980s" without distracting the player.

In addition, as mentioned above, these objects were unlikely to appear within the game itself so their inclusion here avoids players wondering why I didn't reference such "obvious" images.

For the game trailer I've created levels for the 1970s and 1980s.  You'll see more of these on following blogs.

Finally, the bottom of the screen shows a control bar, which is overlaid during gameplay.  Dragging the shuttle left will rewind; right will fast-forward; the speed will vary (in a non-linear manner) according to the distance pulled.  The mark allows a point in time to be memorised, and the rewind button will return to that time -- the idea being that a player will work on a challenge numerous times by trial-and-error.

Finally the record button allows the player to video a sequence; play will play the recording back.  Users will be encouraged to upload impressive or funny clips, similar to those produced by Minecraft fans.

While on the menu screen, the shuttle will navigate through the decade icons and play will select; all other buttons will be greyed-out during the menu screen in the final game.

Peril & Redemption

It's a common problem and we're all familiar with it.  I'd had a stressful week: I'd fallen behind with work and was trying to catch up, but was also being inundated with so many new jobs that I was struggling to juggle both.  (And, of course, all the new jobs have "urgent" stamped across them in giant neon letters.)

This got me cogitating on the walk home: there's a game in this.

Yes, and it's already been made.  Tetris.

Tetris gives the appearance of elegant simplicity -- yet it consists of a masterful and complex balance of design decisions which give optimal flow and incredibly intuitive game mechanics.

Pace & challenge

Joe Hilgard, a psychologist specialising in the effects of video gaming, presents a fascinating case study on his blog, examining the factors that make Tetris addictive.

His analysis identifies the staple mechanic of increasing pace (one of the easiest ways to maintain flow) and the inevitability that a player will reach optimum challenge while playing.  This second factor is a consequence of the first, and is easy to achieve but hard to control.

So how do you control flow?  Hilgard identifies two ways that Tetris achieves this.

• Jump-in at a higher level.  A more confident player may set the initial difficulty level higher, avoiding the tedium of working up to a challenge that matches their skill level.  (This is also the reason why many games allow players to save their progress rather than returning back to the start every time they play.)
• Quick death.  When the challenge bypasses the player's skill level, the game does not last much longer.  This allows a fast re-start to get another 'fix'.

For the game designer, there is -- thankfully -- a margin of error in setting the rate at which the pace increases.  I imagine that many days of QA testing were required to polish this and tune it in like a radio.  (I'm always impressed at how brilliantly pace is set in Nintendo EAD-developed games, and their input in the definitive Game Boy version undoubtedly added some refinement in this area.)

In addition to jump-in, another way that players set their own increased challenge is by attempting a stunt -- the satisfaction of doing something clever like destroying the maximum four rows at once, or letting the wall build to a certain level with the aim of bringing it back down to ground.

Oh, that's sooooo satisfying!

Peril & Redemption

One of the biggest features of Tetris for me is redemption: the possibility of earning your way back from the brink of losing to a position of relative victory.

This is an incredibly powerful tool, exploited mercilessly by Hollywood movie-makers.  Blake Snyder's highly influential screenwriting guide "Save the Cat!" set a template formula which is employed in nearly every major film of the last 9 years:

“We got rules around here, smartass,” the chief growls. “Do yourself a favor. Learn ’em.” That’s Snyder’s second beat, theme stated. And it’s right at the seven-minute mark, almost exactly when it’s supposed to happen in a 110-minute movie. The rest of the Snyder playbook is there, too: a story-starting catalyst midway through the first act, a shootout at the midpoint that ups the ante, an all-is-lost moment — including a death — between the 75- and 80-minute mark, and a concluding final act in which the baddies are dispatched in ranking order, just as Snyder instructs.  -- Peter Suderman, Slate.com

The peril of the all-is-lost moment is followed by victory, snatched from the jaws of defeat (surely the most satisfying type of victory) -- these generate an strong emotional affect in the audience, stronger than that which a simple inevitable conclusion would give.  A bit of "will-they? won't-they?" tension helps too.

It's not just movies.  TV game shows are built on this premise, too.  One contestant is winning at the halfway point, so logic dictates that they will extend their lead further.  Hence the "double money round" which gives the underdog the opportunity to catch up.

To me, this is the main thing that makes the game so enjoyable.  The flow does not just build in a linear fashion to an inevitable conclusion but actually ebbs before rushing forward again.

Variables

It's easy to miss how carefully this game has been crafted.  The well's width & depth each have an effect on the speed at which the player must respond.

Another subtle design variable is highlighted in the Tetris Strategy blog, which introduced me to a term I'd never encountered before: are ("ah-ray").  It's a Japanese word that refers to the delay in spawning a new piece.  By setting this to just the right period, the player can start to plan the movement required for the next piece.  Too short and the player has less control; too long and the game becomes frustratingly easy.

Potential

Tetris is not the only game to make use of many of these concepts.  Bejeweled and Missile Command are other games which combine pace with peril & redemption to create addictive gameplay.

With this in mind, meandering away from my core nostalgia theme, I'm currently considering some kind of game mechanic based on the idea of trying to catch things as they come at you, but with the ability to pick items up from the floor between catches as a means of redemption.  Could be interesting.

Geoff Love and copyright

Copyright & trademark infringement is a notoriously tricky area.  Companies are increasingly litigious nowadays, seeking to grab every-penny-they-can from intellectual property (IP).

Additionally, there is a significant undercurrent of speculative copyright claims, which are sometimes difficult to distinguish from legitimate ones.  This puts the indie game designer in a precarious position.

Pastiche for Profit

There is undoubtedly an art to trying to pastiche popular designs for commercial profit.

I first noticed this when a young lad, after getting two records by easy-listening legend Geoff Love & His Orchestra.  In 1978, mad on sci-fi and spy movies, how could I resist the charms of Star Wars and Other Space Themes?

This album's cover is a masterclass in trying-not-to-get-sued.  (Although one blog suggests that potential litigators may have left them alone anyway, due to feeling sorry for the publishers after hearing the slightly dodgy cover versions of certain tracks!)  The Barbarella image is suprisingly un-adjusted, but I'm guessing that the Tardis is "generic police box" enough to slip through.

(top) Matt Jefferies' Star Trek USS Enterprise
(middle) Star Wars poster by Tom Chantrell
(bottom) Brian Johnson's gorgeous Space:1999 Eagle Transporter

As a youngster (and burgeoning pedant) I was bemused why the spaceships were "wrong" and asked my Grandad, who explained that "they can get into trouble for copying the spaceship so they have to make it look different".

A few years ago I was amused to notice this cover for a Big Finish Doctor Who "Tsar Wars" audiobook, clearly paying tribute to the Geoff Love album cover.

I soon learned that this was a common issue.  I also had a copy of Big Bond Movie Themes, with cover by Tom Chantrell (who'd also painted the official Star Wars poster shown above).  However, on a trip to the local Tesco record section I was shocked to discover they'd (shoddily) amended the cover with James Bond facing backwards!  I'm guessing that somebody objected to a recognisable Roger Moore (and other faces) on the cover; either that or Music for Pleasure's legal team got a little edgy.

Further research reveals countless other examples of this, like the one below:

(top) The Close Encounters images are identical to the originals, but presumably these are considered generic enough.
(bottom) Roger Murray-Leach's Blake's 7 Liberator underwent a number of revisions for this cover.

Although dated, these examples give a good example of the need to be careful when copying designs, especially those related to trademarks.

A subtle combination of vagueness and threat

On the Retail Week website, IP specialist Simon Bennett gives his opinion on copyright infringement in fashion:

"The test in deciding whether a copyright infringement has occurred is whether a substantial part of the original clothing has been copied. This is a qualitative and not quantitative test and there is no fixed criteria to be guided by.  The idea that making seven changes to a piece of clothing will be sufficient to avoid copyright infringement is an urban myth.”

This raises an important question: how much can you alter a design before it is unrecognisable as the original?  When using pastiche, it's vital that the original source is evident.  How can something be recognisable and unrecognisable at the same time?

I think most of the album covers above get away with it, which shows that it's possible without losing the core theme, so long as it's obvious that the intent is to deviate from the original design.  That way it's still possible to keep key features (like with the Enterprise and Liberator) and some core design features.

Another trick is to use generic items in context.  For example, a picture of a uniformed pilot on a sci-fi TV & film album is suggestive of Thunderbirds.

Being innocent isn't enough

Finally, on a more cautious note, it's worth remembering that being innocent isn't good enough -- a designer has to also try to create enough distance to avoid any potential claim.  Regardless of whether infringement has or hasn't taken place, any legal proceedings can be expensive & stressful, and professionally embarrassing.

I was reminded of this recently when watching a biopic of Joe Meek, producer of the famous music track Telstar, which showed the emotional toll after being sued for alleged plagiarism.  Meek had made matters worse by failing to respond promptly and was eventually found innocent shortly after his suicide, but the experience was clearly an unpleasant one.

So, overall, I feel that it's possible to walk a tightrope of pastiche for profit, but there's a vital need to be careful when doing so.

Sophia George at the V&A

Back in the summer I did a case study of the iPad game Tick Tock Toys, which included the development process, aesthetics, game mechanics and also a profile of the lead designer, Sophia George.

My tutor had made me aware of the game a few months earlier; I chose to carry out a detailed case study because it had a number of things in common with my own research: casual gaming, old toys, and combining mechanics with intrinsic narrative; also, the game was developed using the Unity game engine, which is my own tool of choice.

The case study was a fascinating exercise and opened my eyes to a number of factors I'd never before considered.  I'd contacted Sophia with a handful of technical questions and she was kind enough to reply with some helpful and enlightening answers.

Since then, Sophia has commenced her role as Games Designer in Residence at the V&A Museum in London and, among her many duties, is currently working on a video game inspired by William Morris's Strawberry Thief textile patterns.

As as designer-in-residence, she holds regular open workshops so I took the opportunity to visit the museum and drop in to quiz her more, and to get her opinion on some preliminary designs I'd done for a Tick Tock Toys level weaving my own nostalgia-based ideas with her existing structures.

She's a very smart cookie and has had to learn a lot of things very quickly.  Her prominent public profile promoting the games industry -- she's just been named one of Develop's "25 People That Changed Games in 2013" -- has given her great access to explore the wider workings of the sector.  With Sophia's permission, I'd like to publish some of the information she shared with me.

Q&A with Sophia George

The mechanics of Tick Tock Toys are linked to the limited movements of certain types of toy.  I asked Sophia which came first, the toys or the movements (as an abstraction)?  Given that my own designs looked at the items first and extracted a mechanic, I'd expected a similar response.  Hence I was quite surprised when she stated the opposite:

"The mechanics of the game came before its toybox theme.  I really wanted the gameplay to be described simply – such as 'Get the X to the Y'.  I was looking at old games like Super Mario Bros for the NES and saw that the gameplay was to simply get the character from one side of the screen to the other, while avoiding obstacles.

"So for Tick Tock Toys, you have to get the robot from one side of the screen to the other, but you control the object rather than the main character."

So why choose toys?

"The game was designed for a ‘family’ audience, so I thought toys would be perfect!  Children like toys, and parents/older siblings can feel nostalgic.  Toys are also very versatile.  They can vary from country to country, and are different depending on what era they are from.  We kind of looked ahead and thought if the game was mega successful, there was lots of opportunities for expansions – such as Mexican toys, Japanese toys, Bauhaus style toys, 80s, etc!"

My case study gave the impression that she had put a lot of attention into character design, which turned out to be correct: "I really enjoy character design, so its visual appearance is important to me."  She was particularly pleased that other designers had recognised the depth of work that had gone into her designs.

She later explained that the Tic Toc robot -- which I had already presumed was influenced by the Lilliput tin toys of the 1950s -- was originally inspired by the Japanese Keepon interactive robot (see dancing video!)

(left) Keepon; (centre) Lilliput tin robot; (right) Tic Toc

As I'd discovered from my own work, using familiar toys quickly brings up copyright & trademark issues.  I asked her how she dealt with this.

"We felt that we had to be careful with copyright, just in case!  The goal in the game is a Frisbee, but we couldn't call it that because it's trademarked!  I also wanted to have the Fisher-Price styled ['Chatterbox'] phone, but we changed it; the original bear looked a bit like the Japanese character Rilakkuma."

(left) Playmobil knight; (centre) game knight model; (right) final game character

During the case study I became fascinated with the problems presented by the top-down view.  I asked whether it was hard finding the optimum camera angle?

"The camera angle was very tricky to achieve.  A top-down view would be the easiest to achieve, but it would have abstracted some of the 3D models.  All of the artists were firmly against a top down view (one of them told me they wouldn’t work on the project if it was top-down!)  We also have the UI on the back wall, so it was important that it was easy to spot.  So we just did a few experiments in Unity and ended up with what you see in the final game."

Finally, what about feature creep -- was that an issue?

"We finished the core game, with graphics and effects with one month of the competition to spare. This is when we focused on bonus levels and polish, so feature creep was never an issue – I guess it helps to know exactly what you want your game to be like."

My own projects have a habit of spiralling out of control, so this last point was very educational and reinforced what I'd learned elsewhere: make a very detailed plan and stick to it!

At the V&A we chatted about some of the things Sophia had learned from exploring the wider industry, including the need to have very clear leadership on a group project.

Tick Tock Toys contains free levels but further levels need to be purchased as a pack (at a reasonable cost).  One aspect I was interested to know more about was her experiences with freemium / in-app purchasing (IAP).  She had recently visited a major company who operate in this field, and was concerned about the potential ethical problems of this business model, which led on to related topics such as gamification in retail.

I'm extremely grateful to Sophia for sparing time to discuss her work as a designer and certainly found it extremely informative & educational.

Adding a bit of theatre

Back in late November, my tutor Josh threw two brilliant suggestions at me.  The first concerned a deeper analysis of nostalgia triggers; the second addressed an area which I had paid scant attention to, but which I now realise is a major tool of the arsenal of a game designer: "adding a bit of theatre".

Probably the most common theatrics are event-driven animations (or automated actions) with accompanying sound effects, such as explosions or character/NPC death sequences.  These are pretty much a necessity because the game would seem strange without them.

However, any other theatrics -- special animations or sound effects, Easter eggs or special effects -- will undoubtedly take time & effort to produce, adding to the cost of development of a game.  Therefore the decision to include them is significant; a designer (and, critically, a project manager) must ask: "will it add value?"

Such features are usually put into a product at the design stage, because it may be difficult to add new features during the build cycle.  (My conversations with a local game QA specialist opened my eyes to the need to lock down designs tightly to avoid feature creep.)

An end-of-level celebration from the stunning Super Mario 3D World featuring confetti, characters jumping around in costume, and lots of sparkles.

I've become fascinated by the fact that many theatrics in games are optional extras -- sequences that appear to be unnecessary but in fact form part of the cumulative appeal of a game, or adjust the narrative flow.

Making the mundane more special

The seminal DMA/Psygnosis game Lemmings featured 8x8-pixel characters with a fairly simple walk cycle.  According to historical accounts, programmer Mike Dailly produced a basic animation which was then enhanced by animator Gary Timmons.  This improved walk cycle enhances the charm & appeal of the game tremendously, adding personality to the character.

(left) Original walk cycle
(right) Improved walk cycle

Sometimes the value is quite subtle.  Josh drew my attention to the AMEE robot in the film Red Planet, which unfolds in a satisfying and creative manner.  The result evokes a reaction of "that's cool!" in the viewer, enhancing their enjoyment of the overall film (although not enough in the case of that particular film, which flopped badly).

The more spectacular the theatre, the more the player will want to see it again.  This type of idea has a long history in the "coin drop" psychology of arcades & casinos, and is a major feature on many pinball tables.  Just like a Las Vegas fruit machine which employs "extra rattle" when ejecting winning winnings, some games utilise machine-gun-style explosion sequences or shaking to emphasise a big event.

An "ice storm" on Bejeweled 3.  You can see this -- and other animations from the game -- in this short gameplay video.

Narrative flow adjustment

A level may sometimes need boosting to create a climax of some kind at the end of a stage.  This may double-up as a reward for the player, such as a celebration of achievement.

The example below shows this very well.  Two pieces of a relic must be reconnected.  At this point the game might have simply flashed-up an image showing the complete relic.  However, by showing the two pieces coming together -- not just jammed together but rotated, with an eased deceleration -- the event takes on a more magical (and significant) role.

The reunited pieces of the Triforce of Wisdom from Legend of Zelda: The Wind Waker

As Alfred Hitchcock demonstrated, why have a simple fight when you can instead have a fight on an out-of-control merry-go-round?  Theatrics can be used to increase tension.  I managed to do this myself by accident when testing Weeble physics a year ago.  In the animation below, the egg teeters and only just stays on the trailer when it moves.

The flip side of this is the use of theatrics as comic relief.  Cartoons such as Top Cat often employed this, countering boring exposition with background visual antics.  There's a gorgeous example of this in the first minute of the introduction to Orson Welles' Magnificent Ambersons (1942), where a horse-drawn omnibus breaks down outside a house, with visual cues perfectly timed to draw audience focus to-and-from the accompanying narration.

The Money Shot

Some theatrics form a major part of the appeal of the product, especially at the promotional or advertising stage.  A disproportionate investment in small parts may yield increased sales.

Battle Chess (Commodore Amiga, 1988) was a basic chess game which included animated "take" sequences which, on its release, became a must-see for small crowds at my local computer club.  The board game was brought to life with a wide range of variant deaths (including one where a character was sliced in half, sliding apart), some paying tribute to popular movie scenes.

Microsoft's much-berated Windows Vista software included a new feature called "Flip 3D" which allowed users to cycle through windows at a perspective angle.  Some critics argued that this was a flashy & useless addition, duplicating an existing "switch task" function.   However, they missed the point.  Vista had a PR problem before it even launched: the main changes to the software were "under the bonnet", and there was very little that stood out as a "soundbite" for reviews.  Flip 3D was not aimed at the user; it was aimed at magazine articles which needed screenshots, to add a promotional "wow" factor.

Latent theatre

One of the main things I picked up from Josh is the idea of latent theatre.  Some objects have a potential dynamic that just screams out "something can happen here!"

Josh's examples included:

• A partially unspooled cassette tape sat beside a pencil
• A top-loading VHS player, waiting to be pushed down
• A stuck-down spring jumping toy

Having cogitated on this, I realised that this works best with devices that have a self-evident or well-known mechanic, especially when "primed" (i.e. set up ready for an obvious action).  Other examples are:

• A big red button.  Must be red.  Must be fairly big.  Preferably with a sign saying "Do not press".  Regardless of the outcome -- and there must be an outcome, no matter how small -- this is a hard thing to resist.
• Any item poised at the edge of a diving platform.  (This works better if the platform protrudes, to imply that the object is meant to fall.)
• In a similar vein, a plastic ruler jutting out from the edge of a desk, waiting to be "twanged".
• A match sitting near a matchbox.
• Firework, rocket or dynamite with a prominent fuse and nearby flame source.

This is a fascinating area, suitable for much deeper study at another juncture.