Oh, same thing happened to me. It is quite important you specify bronze difficulty when you're starting out.

The multiplayer mode is surprisingly addictive. Be sure to give that a try… Just try not to get so wrapped up in it you never finish the main game!

I used to feel like I wasn't getting my money's worth if I just blew through the game's main story while not letting myself enjoy the side content, so I took my time. After a while of doing this I had nearly an entire shelf of unfinished 360/PS3 games. Now I put more focus on completion, while maybe allowing for a few…