Running NIBs in Vice?

[Retroguy]

Hi! I'm trying to use Vice to run the C64 Thundercats game (which I've always wanted to play since it's the only Thundercats game there's ever been) but the file is NIB format and I can't figure out how to make it go. Can anyone help me?

[Retroguy]

Okay, I went to another site and found the correct file format for the game. At the title screen it says to push the fire button to start. When I push the button, nothing happens, the game won't start. Am I doing something wrong?