THE HOUSE OF THE DEAD: Remake

As the description says, you need to play through the game from start to finish in co-op. When starting up a new campaign, make sure you enable cooperative mode (or competitive, if you want), and then have two controllers set up (there is no online play). There isn't much different in co-op other than some extra enemies here and there. If you're using cheats, it's really easy to just leave the second controller idle and play through like normal with your main controller. Even without cheats, on Easy it's still completely practical to play through solo considering you have so much health and 10 continues.