Yeah, well... I was rather thinking about multiplayer code, but it's true it does apply to offline game mechanism as well .
Let's see... How many things did Cyan break when upgrading Plasma ? Hmmm, the Wall, the Marker Games (I played Capture and Hold marker games on offline UU, they are a lot less buggy than on CC), the Heek, IIRC some KI functions, and now the Zandimobile .
Using the spacebar to reset the car must be quite useful, considering how wrong the collisions are. Yeah, when the car doesn't fall through the floor, it flies in the sky.
I remember I set up an Age with a drivable jeep once... it was fun, but even with simple collision fields the thing was still buggy Too bad, it could be quite useful to explore large Ages...