He is looking for local multiplayer. It has been requested very often already, for all gamemodes (even standard lol), and the answer is in short:
This would only be possible in taiko and ctb, standard would be ridiculous and mania would have keyboard ghosting issues as soon as both players have too hit a quad at the same time. If we ever get to see this is unlikely, but for further information refer to other posts that requested this (too lazy to link them)