Will I be able to return this game.?

Today I got Terminator Salvation and finished it in about an hour. It was OK but I don't think it was worth the �25 which could of been spent on the UFC game. I got it from Xtravision by the way. It say's on the reciept that unwanted items may be returned in saleable condition. I removed the plastic package so does that make this void. The disc and case are in perfect condition though and the DVD that came with it is the same way. Will I be able to return it for full credit.