Emu-coop works well for any game that has locks and keys and backtracking.
It currently works with Legend of Zelda: A Link to the Past the Link to the Past Randomizer Legend of Zelda for the NES (plus its randomizer) and Super Metroid and its randomizer (although for Super Metroid, you might want to check out Multitroid instead). This is an emulator hack that turns 1-player games into 2-player games by sharing in-game inventory over the internet.
