i have to say i like both games. I played half-kufe 2 the day it came out and loved, it is as close to perfection as a game can be. However i hav just finished playing halo 2 on my mates xbox, we finished it on normal in about 5 hours and although it is very enjoyable it is not as great in terms of innovation, and player inclusion as HL2. It feels like halo on steroids. with the new features just added on to the original halo formula. But it is not as good as HL2 it adds hardly anthing new apart from the multiplayer (which is great). my only real pro for halo against HL2 is that it is alot of fun when playing with a m8 in coop, halflife 2 cant touch the xperience of helping each other take down hunters it is sooo much fun:) but when sven 2 cmes out even this will be inquestion. in my opinion anything halo 2 can do halflife 2 can do better.