More details are needed. How did you get this file?
If you just found this on a game CD, then it is probably some proprietary format devised by the developers and you will have to reverse-engineer its content manually, i.e. through trial and error, or by debugging the game while it is running.
If you think it might be graphics, then you can try opening it in Tile Molester. Online TrID
might be worth a try as well.