OP4 Is the Citizen Kane of games. Play it now if you have not already. The deathmatch and CTF are AMAZING and FUN and the story is great. The gameplay is FUN and the weapons and hostile's are very awesome. The ally marine AI is bad but it is old too. The ally marines may stop following you or randomly shoot you. If you shoot your ally marines they become hostile and will shoot you. The voice work is amazing and all the marine line are memorable and quotable. The music is amazing. The story is amazing. The controls are a little slippery. It needs a sequel and in my opinion, it is the best game of the half-life franchize. SO JUST PLAY IT ALREADY!