why not add some kind of Storyboards that Ouendan and EBA has in Multiplayer matches? when a player is going well in a game, the animation of the storyboard changes. and when a player strikes a combo, fills the Fever gauge. if a player manages to fill the Fever gauge, it will trigger the Fever mode on his/her opponents, giving them a random Increasing difficulty mod for a short amount of time(Sudden Death and Double Time are not included)but beware, because if you decide to trigger the Fever mode ON, you can't use any other Mods(all mods that were enabled before Fever mod will be disabled automatically)
the amount of time required to activate the Fever mod depends on if you strike a Beat combo(slower) or a Elite Beat combo(faster)(all these suggestions are only available for Multiplayer Matches)
the amount of time required to activate the Fever mod depends on if you strike a Beat combo(slower) or a Elite Beat combo(faster)(all these suggestions are only available for Multiplayer Matches)