An accomplice is a person who actively participates in the commission of a crime, even though they take no part in the actual criminal offense. It isn't required that they profit from the crime, and often they don't.

Gamasutra covered how much of a scam this contest is.

The executive summary: Atari gets full ownership and rights to every submission, winning or otherwise, and you'll never earn anywhere near $100k even if you win the top prize.

All of this is rather unsurprising, given the dirty tricks Atari Legal have been playing lately.

Another case where estoppal applies - they've let homebrewers use the fuji logo for decades now without a single takedown notice. Apparently Atari thinks they can sell more Fuji logo mugs and shirts at Target if they push around those that kept the flame alive.