B/c music covers are explicitly covered by licensing laws. Videogame covers are just unimaginative copies (which may also violate copyright laws covering derivative works).
If you want to make a game, make it like the game you are copying, but make it unique. Change the graphics. Add new enemies. But don't make the same game.
It seems everyone has read the post in a different sense than I'd intended. I'm not suggesting that people pass copycat games off as originals. It just might be a good workout.
For example, a lot of the fun in DOOM has been (in my opinion) lost in later generations of FPS. An honest attempt at copying might have helped game designers capture the little details that made the game fun - not just the general idea of "whoo I'm a first-person shooter".
If you want to make a game, make it like the game you are copying, but make it unique. Change the graphics. Add new enemies. But don't make the same game.