Adrenaline rush for John? + Another ability? [KYL:TG]

During development of KYL:TG, I realised that my idea for John's gameplay isn't really that fun. Being slow doesn't bode well with a platformer shooter.

So I had the idea of gradually increasing John's speed the more you kill, like it's getting an adrenaline rush. This'd make it so that the player has an actual incentive to kill, considering it also increases tension so thus the amount of cops.

I'm also considering adding another ability to everyone, but I'm not entirely sure. So far Sonc has the most fun gameplay, so if I were to add any new abilities, it would have to also work well with Sonc's gameplay. So far no ideas.

Again, any feedback is very appreciated.
Thanks for reading!