CAVE STORY / Studio Pixel / PC
It is not uncommon anymore to see fan-made translations of games that were only released in Japan, but generally this only applies to popular commercial releases. It's pretty rare to see anyone bother to translate an amateur piece of freeware, but Cave Story is a pretty unusual and exceptional piece of freeware. Created and released by Daisuke "Pixel" Amaya in 2004, English fan translation group Aeon Genesis very quickly put together a patch for it and got Pixel's blessing to bring it to those of us in the English-speaking parts of the world.
It's a run-and-gun action game whose non-linear structure is reminiscent of Metroid or the more recent Castlevania games, but to me the gameplay resembles that of Mega Man more than anything else. You play as a small hero exploring a large underground world, initially with only the ability to jump, and to fire a cannon that upgrades as you pick up chunks left behind by defeated enemies (and downgrades as you take hits). Aside from the shooting and the looting, there's also a lot of precision jumping over pits and spikes that cause instant death, but unlike most Mega Man games, save points are plentiful.
The story is an odd mix of lighthearted goofiness and tragic pathos. You play as some sort of rabbity thing saving a group of other rabbity things from being experimented on by a mad scientist, and are frequently interrupted in your quest by a bounty hunter who also happens to be a toaster, yet the game has some genuinely sad and affecting moments. Aside from the very smooth and polished gameplay and level structure, this is a major part of the game's appeal and mass popularity. The graphics are simple, but very serviceable with some nice weapon effects, and the music sounds a bit like that of the Kirby games with a more ambient touch.