Jazz Commander: You, Spaz, and Lori act like a team of army men. You command Lori and Spaz as your two soldiers. So you could tell Lori to hold position, and tell Spaz to follow you, and then tell Lori to go in for an assault. You could also switch leaders and stuff. First to die loses. Spaz and Lori could also have a set number of lives and stuff.

Juggernaut Mode: (not my idea) Bullets do double as much damage, they are twice as big (that would involve editing clients j2a files which would be nearly impossible). He can also run faster (2x client speed hack shouldn't be that tough). The juggernaut gets like 30 seconds and everybody has 1 health and the juggernaut kills as many rabbits as possible in that 30 seconds. Then it rotates to another rabbit.

Dodge Bullet: Shoot the rabbits. When the rabbit gets shot he gets warped and becomes one of the shooters.

Cops and Robbers: Rabbits start out with a chosen amount of coins. Every time they get tagged they lose a coin. When they run out of money they become a cop or have to continue to tag other players until they get a coin back and then they try not to be shot at/tagged.

Pit Fall: Random triggers hit at any random time never repeating the same cycle, causing rabbits to fall through the floor. When floors open, other rabbits try to shoot their enemies down. Last rabbit standing wins.

Musical Chairs: That shouldn't have to be explained and you probably wouldn't need to modify jj2 to do that, you'd just need to make a level with lots of triggers (which I may work on when school's out).

Need more ideas but i'm presenting these because personally, I've lost all interest in Jazz Jackrabbit 2 and I think stuff like this would make it more interesting. I will add more ideas as they get posted.