You need to restart your computer... Mac.?

Alright so recently I bought a new imac. A few weeks ago. Now I downloaded an illegal game, and the first few times I ran it, it ran perfect. But Just before I exited it and then it came up with the black screen of death, the "You need to restart lah blah blah, hold down the restart button... bnlahadh". Ok so what I would like to know is, is the game causing this?