[KenWittlief]

is 90 degrees also considered tilted? If a robot falls over its ok to push it around, no requirement to push it by ITS bumpers only?

That would make sense to me. Having a robot become more or less untouchable just because it falls over would make for a pretty lame competition.

Anyone remember the game of 1999 - when you had to get up on the 'puck' at the end to score extra points? Holy cow, the pushing and shoving matches that happened in the playoff rounds that year. Some robots literally dragged opponents off the puck with arms and grabbers. Made for one heck of a spectator sport that year.