The removal is due to a copyright claim made by the Tetris company.
Well — I've received notice from Apple that they've been contacted by The Tetris® Company about Tris. That, I'm afraid, is essentially game over. Do they have a case? No. Not really. I am convinced that if it went to court, the "copyright" claim would get thrown out completely. The trademark, perhaps not — but if I changed the name, to e.g. “Trys”, that would be much harder for them to argue.
Witherspoon reports that as a college student he does not have the resources to fight this action and so the application will be removed on Wednesday.
Tris is a free download and remains in the App Store at this time. [Download]