@Dio_Vento has recently released his ROM hacks of Pokémon Sun and Pokémon Moon. Based on his previous work, Pokémon Rutile Ruby and Pokémon Star Sapphire, these hacks aim to provide a legitimate challenge to players seeking something more from the latest Pokémon games.
Here's the trailer:
Features include (but are not limited to):
Harsher level curve
New trainer & gym teams
NPC's using Mega Evolution
Improved item availability
Trade-based evolutions can be done in-game
Downloads, as well as more information, can be found in the project thread.
Nintendo has released update 11.3.0-36. It patches safehax, so if you do not have CFW installed, do not update if you wish to install it (instructions can be found here). Without CFW, updating will prevent you from using save editors like PKHeX or ROM hacks until homebrew is updated.