<p>Playing though Halo 1 and 2 with a friend is the absolute best way to experience the game. It gives you more options and more strategy and it is generally just a heck of a lot of fun. “Accidentally” running over your friend with a Warthog or killing each other until the bodies are stacked ten high are added bonuses. Co-op is offline.</p>Just like Halo, the TimeSplitters games are even better when you play with a friend. There are all sorts of fun hidden references and other goodies and it is a goofy lighthearted experience that is at its best when you play with a buddy. Co-op is offline.For zombie fans (such as myself and my friends) Stubbs the Zombie is a dream come true because you and a buddy can take control of zombies and create your own army of the undead. Eating brains and infecting humans is a hilariously fun experience that is best shared with friends. Co-op is offline.Playing through X-Men Legends I and II with a friend gives you a whole lot more strategy and crates a much deeper and more entertaining experience. Co-op is 2-4 players offline in Legends I and 2-4 players both off and online in X-Men Legends II.Shaolin Monks takes all of the cool stuff in Mortal Kombat \u0096 the blood and fatalities and cool characters \u0096 and strips away the bad stuff (like the cruddy fighting engine). What you are left with is a solid beat-em-up that gets even better when you can work together with a friend. New moves open up when two people play and it is impossible to beat it 100% without playing some co-op. Co-op is offline.<p>Co-op in Chaos Theory takes place in unique levels that were designed with two players in mind so it is a completely new experience from the single player game. You have a bunch of new moves to use and playing with two people opens up all sorts of strategy that the single player game lacks. Co-op is available in splitscreen as well as on Xbox Live and system link.</p><p>Doom 3 is a scary game, but you can be a bit more confident when you know your friend has your back. It makes the game quite a bit easier when you have two people blasting demons, but it is considerably more fun. Co-op is available over Xbox Live and system link only.</p>Lego Star Wars is cute and a tad on the easy side, but it is still Star Wars darn it. You have dozens of characters to choose from and it is a lot of fun to play through with a friend hacking up enemies with your lightsaber. Very fun for Star Wars fans. Co-op is offline.Ghost Recon relies heavily on communication and teamwork, so it is no surprise really that co-op works so amazingly well. You can count on your friends to play a lot smarter than the AI which introduces new layers of strategy and depth. Co-op is available in splitscreen and Xbox Live.Serious Sam II is a simple, straightforward shooter that doesn\u0092t really add anything new to the genre but is undeniably fun. Even better is that you can take it online and play co-op with up to three other people and the best part is that the game ramps up the number of enemies in the level depending on how many people are playing. Genius! Co-op is available on Xbox Live.