One of the highlights of this year's Austin GDC was a session by game design veteran Greg Costikyan on the 'blight or bane' of randomness in games — a wide-ranging talk that covered the history and delicate balance of luck or chance in games, and their interplay with the idea of skill.
Of particular note were his final slides on algorithmic content: randomly or procedurally generated games, starting, of course, with the genre-defining early computer RPG Rogue, a game highly dependent on luck but also one of near infinite variety with each successive playthrough.
The idea is one that's been prevalent throughout videogame history, but it's also one that's most recently and notably being embraced by indies for its exploit-ability in adding 'cheap' (once your algorithms have been perfected) content and replayability on a tight budget and tiny team.
Derek Yu's Spelunky (at top) is easily the best example, and where all discussion of the indie embrace of procedural generation needs to start. Taking the Rogue formula and applying it to the 8-bit platformer genre, Spelunky's enduring power and charm (having been finessed for nearly a year, and only just now hitting its 1.0 release) is its ability to create "situations" rather than rote level layouts.
Though your only goal is 'simpy' to reach an exit at the bottom of each generated cave, without the benefit of memorization (think of how easily, 25 years later, you can now anticipate each impending Goomba and pitfall in World 1-1 of Super Mario Bros.) every new twist in Spelunky is a fresh test of more overarching skills: arrow-traps lining the walls of your next drop, a giant spider hovering near a precious gem, a distressed damsel crying for help at the bottom of a snake pit.
None of these situations are ever presented the same way or in the same sequence twice, nor are their solutions any less unique, and each failure presents a learning opportunity that feels as rewarding as each victory (particularly in how it avoids the Groundhog Day frustrations of butting up against identical deaths). Play Yu's free PC release of the game and you'll understand instantly, and prep yourself for the 2010 release of the Xbox Live Arcade version.
Adam Saltsman's embrace of these ideas goes even deeper: his decision not to include GUI level-editing utilities in his recent free Flixel Flash engine was meant to encourage new developers to experiment with script-based procedural techniques, starting with his own game Fathom (and Flixel demo game Mode).
Where that's shined most brightly, though, is in his Experimental Gameplay contribution Canabalt (just recently released for the iPhone [App Store link]). Stripped down even further than Spelunky, Canabalt is one-button economy over-top procedural play. Your only interaction in Canabalt is to jump from roof to algorithmically-heightened and extended roof in a break-neck escape from a situation unspecified, giving the game a laser-focus on speed and reaction time.
It's that simplicity and variety that's made it not only one of the most compulsive indie games of the year, but also the near-instant viral hit it's now become (alongside Saltsman's smart social network promotions).
Finally, procedure meets sandbox in Farbs' Captain Forever, the least overtly or recognizably generated game of the three, but no less infinitely replayable, as signified by its title.
Your goal in the game? Merely to act and excel as a star pilot — and by 'you' I mean 'you': Forever's best fourth-wall-breaking trick is to use your PC's webcam to project your own face as a ghostly reflection on its low-bit display, visible primarily on direct-hit enemy explosions, which places you directly inside your ship's cockpit even as you sit slumped at your MacBook.
To progress further into its infinite universe, Forever lets you procure scrap from demolished ships to build your own ever-more-fearsome craft, which elicits a further push-pull by generating both more powerful foes with higher-grade shields and weapons, and easier prey as you lose your own components in firefights.
Still in pre-release, you can donate to Farbs to get an early look into the infinite space of his generated space, and, as with the other games above, become a firm believer in the church of procedural gaming.