Anti-particles: It would be nice if we had an option to (pay to) reshuffle the board, or even just wipe and refill it. I can't get better than a 1.3 multiplier right now because most of the board is full of singletons.
Entertaining, but the physics are atrocious. Seemingly innocuous bounces will suddenly flip the car end over end twice (and once in the other direction) while the bike just sits there.
Give a cookie to your scientists