>>56006509Gaia has a similar feel to the official mainline games while being a bit more challenging
Unbound is fairly challenging but not to an absurd degree like true difficulty hacks. It also has an easy mode too. The game often throws you in fights that have some sort of gimmick to them.
Insurgence (fan game not rom hack but who cares) Is similar to Unbound but it has less gimmick battles and it’s plot is a lot more fanficy. The game has a lot of optional challenges you can enable at the start of the game (Nuzlocke, Solo Run, Wonder trade mode, etc).
Snakewood is great if you are a masochist but terrible if you only like good games.
This gym of mine is very short and the gimmick is that you run a Pokémon gym. You specialize in a type and have to defend your gym from challengers.
Those are all the rom hacks I have played aside from WaterRed which isn’t worth mentioning.