I consider MW2 to be even better than CoD4 which is pretty amazing, but it had so much going on. Bonkers campaign, the introduction of the Spec Ops co-op mode, bonkers multiplayer with a lot of stupid broken stuff and it was funny seeing all the exploits before they got patched out. Never forget the Javelin glitch. Hell, the fact that the Javelin was even in multiplayer was hilarious.