My jury (a small cadre of mice in my garage that I use as a sounding board for game criticism) is still out on whether
Dead Man's Chest is a multiplayer game with a single-player hook, or the other way around. What we do know is that the two games could not be more different. Rather than just play through a 3D action/platformer that is the single-player experience, multiplayer goes for vehicle combat and lets you battle between ships on the high seas.
There's room to argue that the single-player game was the feature at one time, since it does look so darn good. But, it gets deadly boring after just a few levels, because the action is so repetitive. Fighting enemies with swordplay comes down to three or four combinations you'll use again and again and again. This mode is so linear that when enemies come running up, you see, floating above their head, the button you press to fight them. It's like a rhythm game, but not fun like a rhythm game. The .A.I...well, I'll get to that. The amount of fluid control possible is just about nil, so the times you aren't battling tend to be the most dangerous. Falling down holes, jumping in the wrong places and getting crushed or cut is a constant. Like most 3D platform titles, an Easter egg hunt ensues and the game runs you through level after level of different enemies fighting exactly the same way.
For variety's sake - and you'll need it - there is the multiplayer mode. Game sharing is the default, with no limitations at all on what opponents can do in the game. Instead of the platform action, each player boards a ship and proceeds to sea to do battle. The battle modes are standard frag-fest fare, but points for originality in not just offering a few mini-games and calling it quits. It's almost like multiplayer is a completely different game. My guess is that players will spend more time with their friends on multiplayer, since there only needs to be one UMD in play. The single-player is just painful, and in an odd marketing strategy, Pirates of the Caribbean: Dead Man's Chest multiplayer doesn't sell the single-player experience one iota. So, the mice and I decided this game is just confused.