I have a dumb mod idea for osu!standard and it is the "Spinning Mod". It will spin the playfield and the notes will move around making it harder to aim and the higher your combo is the faster the playfield spins. It may be harder to aim but the player can gain a lot of aim PP from it so there is the benefit for this mod. The cons I see for this mod is that it is probably hard to do streams and it is probably hard to code but I guess it would be a fun mod for osu!. I dunno