In this case there's an easy solution: release it and see who sues.
Better idea would be to claim that you're going to release it "real soon now" and then see who sues to stop you. That way you aren't hosed for any expenses associated with actually getting the game ready to release.
"The whole problem with the world is that fools and fanatics are always so certain of themselves, but wiser people so full of doubts." -- Bertrand Russell (I think...)