Ziggurat (iOS)

A number of excellent iOS games have come out recently that can be summarized by the following: “Here is a thing that is fun to do. Do it while we try to kill you. Your performance will be judged on how many times you do the fun thing before you die.” (Now that I’ve written that out, that’s sort of profound.)
Of these, Canabalt is probably the best-known. Bit Pilot is no slouch, either. Super Crate Box has been turning a lot of heads over the past couple of months. Bumpy Road and Pix’n Love Rush probably fall into this category, too. Tim Rogers, who writes about games and is probably a smart guy because he gets made fun of in the Kotaku comments section a lot, has long argued that an infinite mode, with no apparent rewards other than being able to continue playing the game, is the sign of a truly good central mechanic. He’s created a game that falls roughly in line with those mentioned above. It’s called Ziggurat.
Ziggurat casts the player as a human atop a mountain tall enough to reach above the clouds. The rest of the human race has been eradicated by “alien freaks,” and it’s up to the player to kill as many of them as possible before dying. It’s no surprise that the aliens wiped humanity out: Their touch is fatal, and they can (presumably) only be killed by the effects of the player’s energy gun.
The gun fires balls of energy. They can be charged by holding a finger down on the screen. The gun is aimed by sliding that finger from left to right, and fired by removing the finger.
The best part: When charging the gun, you can’t just keep your finger parked on the screen until the perfect shot presents itself. As it’s being charged, the gun gets stronger, reaches its strongest point, then gets weaker again and stays there until it’s fired. The amount of charge time required to fire the optimal shot is excellent. It’s somewhere between three-and-a-half and four beats, just awkward enough that muscle memory will resist learning it, thereby keeping the player on his toes. (Muscle memory, timing, and video games: The fact that many people of a certain age group can, to this day, make Mario fly in Super Mario Bros. 3 with their eyes closed and the television on mute.)
The two most common types of alien have heads that oscillate in size. If you shoot an alien with a sufficiently-charged bullet, they explode, killing aliens within the blast radius. The size of the explosion is a function of alien head size vs. energy ball size. Big head + big energy ball = big explosion = more dead aliens.
Some types of aliens are immune to explosions caused by other types of aliens. Some types of aliens are immune to explosions entirely. If most types of aliens walk into the energy ball while it’s still attached to your gun, they will die but not explode. The most infuriating type of alien can’t be killed until it hurls itself towards you from across the screen, faster than anything else in the game can move.
Ziggurat thrives on these types of edge cases. Keeping the action set minimal while providing a wide variety of gameplay situations forces the player to get creative. Even in a short burst of play, it’s pretty easy to discover a permutation of the gameplay that had previously gone unnoticed.