The title literally explains what this is. I have a lot of friends who play different gamemodes, and its a shame I can't play with them just because they're proficient in another mode that I don't play. I was thinking maybe like a co-op where your scores add together to form a large score? I know that since the scores aren't equal between gamemodes, there would need to be adjustments to the coop score between gamemodes for this mode(for instance all gamemodes having the same score/combo ratio as standard). I feel like this would be really fun and bring the osu community together more. Of course another issue brought up would be the fact that there are gamemode-specific maps, so only all-gamemode maps would be applicable in this.
TL;DR : A Rockband-type multiplayer mode for osu!
TL;DR : A Rockband-type multiplayer mode for osu!