Asteroids, on a screen that wraps at all four edges. Turn, burn and fire, and keep breaking the rocks down until there is nothing left to hit you
Hit a rock and it does not disappear — it splits into two of the next size down. A large rock becomes two mediums, a medium becomes two smalls, and only a small one is gone for good. So a screen with a handful of large rocks in it is a screen that is about to become a lot busier, and the moment after a good hit is the moment to move.
English draughts (checkers) for the original Game Boy — standard rules, compulsory captures and multi-jump chains, against a built-in machine opponent.
A homebrew first-person raycaster for the original Game Boy: four randomly generated maze floors, keys and doors, grunts, bats and brutes, and three save slots.
A port of the 1983 ZX Spectrum classic to the original Game Boy: twelve eggs, ladders, hungry hens, and seed that stops the clock if you reach it first.
A homebrew pseudo-3D racer for the original Game Boy: three tracks, two rivals plus traffic, hills, bends you can see coming, and 27 lap records saved to the cart.
A lunar lander for the original Game Boy: bring the ship down on a pad, in one piece, without much fuel to spare. Gravity is always pulling, the engine is the only thing that beats it, and fuel is the whole clock.
Classic 10×10 battleship for the original Game Boy: a seven-ship fleet that never touches, and three AI levels up to a HARD mode that maps your ships.
Three tracks, two rivals, traffic, hills and a road that bends towards the horizon, on a Game Boy with no 3D hardware at all. GB Racer is a proper arcade racer in a 128 KB cart.
Four random maze floors, three kinds of monster and a gun, rendered in true first person on a 1989 Game Boy. FPS Dungeon shouldn't work. It does.
We kept rebuilding the same Super Game Boy border kit for every game, so we fixed its bugs, added real tests and gave it away. Here's what's in GB-SGB-Tooling.