In my opinion, you can't compare those 2 games together. Different companies, different idea, different gameplay. Yes, it's still an FPS but it plays different. Hell, they're in a different engine too.Replying to Theo Papke above...God...Of course Half-Life 2's story is related to Half-Life 1! It's just set some years later.Gosh, if you're a fan you wouldn't make such a critical mistake.Ending, another reason why they can't be compared: Half-Life 2 tried to take a more realistic take on something that could happen in such an experiment. Halo doesn't seem THAT realistic to me.Then again, I'm arguing with posts from 3 years ago and from 2 months ago.