I thought that was exactly how copyright works. It is infeasible to keep track of every infringement, so a policy like that is unenforceable.
Also its not out of the question that those myriad of tetris clones each secured some sort of agreement with the tetris company.
missingno@fedia.io 7 hours ago
This is a myth. You're thinking of trademark genericization, but even that can only happen in very extreme cases.