I went and downloaded a bunch of bootleg NES, SNES, GEN, GB, and GBC games just a month or two ago. There's a bootleg games wiki that's a good place to learn about them and many can be downloaded from classicgames (dot) me, with a few also on emuparadise, romhustler, and theisozone. I try to avoid the shit that's just spritehacking and go for the actually "new" games. Unsurprisingly, most bootlegs are just ripping off the really well-known stuff, mostly Mario, Sonic, Pokemon, and Disney. I will say I enjoyed the unofficial Pokemon fighting game for SNES and Gen, as well as Donkey Kong 5 and Final Fantasy X: Fantasy War for GBC. What surprised me the most was that people actually put some effort into turning the bootlegs into decent games. The Super Mario World for NES bootleg has an improvement to make it play like the original, the Final Fantasy VII for NES bootleg has a couple of improvement/translation patches, and Final Fantasy X 1-3 (demakes of Final Fantasy IV for NES) also had a basic menu translation path, all available on romhacking (dot) net. It is also worth mentioning that a bootleg called Grandad Seven (aka Super Mario Bros 7, a reskin of a Flinstones game and one of dozens of reskins sold as Mario sequels) caught the eye of normalfags because one of the V-sauce guys did a video or something. There was an effort to remake it as an actual game, which may or may not still be ongoing. Just something interesting I found.