Pokemon Unbound is my absolute favorite of the newer rom hacks to come out in recent years. It has Pokemon available from gens 1-7, and even some mega evolution action.
It has so much more new and custom content in game, they really push the limit for what the base rom (Fire Red) can do and you can really tell that Skeli789 (the game developer) really put his all into the game. This game probably has some of the most unique gameplay I’ve seen in any rom hack. I highly recommend this game to everyone
Additional game info
Link to the official Pokemon Coders page for this game. (No direct game download, only patch file)
Direct download links, prepatched ROM (ready to play)
I can not agree more