Similar to Hardtype hacks, Simplified releases make changes to the game levels, characters, enemies, items, etc to make the game easier and possibly more enjoyable for gamers that have trouble with harder games.  Since these are fan hacks they may, or may not, be as well balanced as the original releases.

NES:
Castlevania (Action)
Legend of Zelda, the (Action/Adventure)
Mega Man (Action)
Mega Man 2 (Action)