pop n' music Sunny Park (or maybe some other pop n' music game has it who knows) has a "Battle Mode" which allows either player to activate a modifier based on their character's choosing. In The Groove, StepMania, and maybe a few other games have the same thing.
How it would work in osu!:
When any player in the match gets his meter high enough, a random effect will be applied to a random player.
Possible effects on each level:
Hidden - Lv. 1 - 25% blockage of playfield, very slow increase based on combo. - Lv. 2 - 40% blockage of playfield, regular rate used in mod. Lv. 3 - 25% blockage, however the darkness climbs up at a incredibly fast rate.
Accelerate - Lv. 1 - Increases speedrate by 1.25x. - Lv. 2 - Increases speedrate by 2.00x. - Lv. 3 - Increases speedrate by 3.00x. (This means it pretty much multiplies current speedrate number by how much it is. On Lv 1., rounds the number.)
Break - Lv. 1, 2, and 3 - Same as Accelerate, however, use - instead of +.
Courage Shaker - Lv. 1 - Will sometimes change judgement to misses and breaks combo at random, however, it actually doesn't. If you keep playing good, the combo, accuracy, and your judgement will still be the way it was. - Lv. 2 - Random points where effect appears is moderately more common, length of effect is more common. - Lv. 3 - Random points and length is much higher.
Spike - Lv. 1 - Difficulty to opponent changes to a higher difficulty by half a star or more (or more being if none exists that's half a star higher.). - Lv. 2 - Difficulty increases by a star or more. - Lv. 3 - Difficulty increases by 2 stars (or to hardest?).
Increase - Lv. 1, 2, and 3. - Changes approach rate, overall difficulty (judgement window). Gets higher based on level. 2 is Hard Rock.
Add - Lv. 1, 2, and 3. - Adds notes. 1 makes all areas doubles if they aren't already, 2 makes areas triples, and 3 randomly shuffles the notes in different positions. (a 4k chart could shuffle a jump (left and right) to a corner jump (right and up/middle right).)
There are no lifebars in this mode, but the lifebar stays as a powerup indicator. Glows brighter based on what level you're at. If you're in the lead, your powerup meter fills up much slower. If you're last, expect to deal powerups more often. The game will popup saying what powerup you're hit by, what level, and who it was from. Score doesn't matter in this game mode either, so accuracy, score, and other scoring modes are gone. Adding mods are disabled. And again, it's impossible to fail.
If having a powerup trigger after the bar fills, you could have 3 seperate lifebars, and fills up at a moderately slow rate, similar to pop n' music, and you have to push a button to trigger it at each level. What the powerup is will be shown next to the lifebars.
I don't know of any other powerups or things like that, and I don't know if this will ever get implemented. It's a nice idea for a party-type competitive play mode.
How it would work in osu!:
When any player in the match gets his meter high enough, a random effect will be applied to a random player.
Possible effects on each level:
Hidden - Lv. 1 - 25% blockage of playfield, very slow increase based on combo. - Lv. 2 - 40% blockage of playfield, regular rate used in mod. Lv. 3 - 25% blockage, however the darkness climbs up at a incredibly fast rate.
Accelerate - Lv. 1 - Increases speedrate by 1.25x. - Lv. 2 - Increases speedrate by 2.00x. - Lv. 3 - Increases speedrate by 3.00x. (This means it pretty much multiplies current speedrate number by how much it is. On Lv 1., rounds the number.)
Break - Lv. 1, 2, and 3 - Same as Accelerate, however, use - instead of +.
Courage Shaker - Lv. 1 - Will sometimes change judgement to misses and breaks combo at random, however, it actually doesn't. If you keep playing good, the combo, accuracy, and your judgement will still be the way it was. - Lv. 2 - Random points where effect appears is moderately more common, length of effect is more common. - Lv. 3 - Random points and length is much higher.
Spike - Lv. 1 - Difficulty to opponent changes to a higher difficulty by half a star or more (or more being if none exists that's half a star higher.). - Lv. 2 - Difficulty increases by a star or more. - Lv. 3 - Difficulty increases by 2 stars (or to hardest?).
Increase - Lv. 1, 2, and 3. - Changes approach rate, overall difficulty (judgement window). Gets higher based on level. 2 is Hard Rock.
Add - Lv. 1, 2, and 3. - Adds notes. 1 makes all areas doubles if they aren't already, 2 makes areas triples, and 3 randomly shuffles the notes in different positions. (a 4k chart could shuffle a jump (left and right) to a corner jump (right and up/middle right).)
There are no lifebars in this mode, but the lifebar stays as a powerup indicator. Glows brighter based on what level you're at. If you're in the lead, your powerup meter fills up much slower. If you're last, expect to deal powerups more often. The game will popup saying what powerup you're hit by, what level, and who it was from. Score doesn't matter in this game mode either, so accuracy, score, and other scoring modes are gone. Adding mods are disabled. And again, it's impossible to fail.
If having a powerup trigger after the bar fills, you could have 3 seperate lifebars, and fills up at a moderately slow rate, similar to pop n' music, and you have to push a button to trigger it at each level. What the powerup is will be shown next to the lifebars.
I don't know of any other powerups or things like that, and I don't know if this will ever get implemented. It's a nice idea for a party-type competitive play mode.