Andy_Panthro: I was wondering... do third party Source-engine games (such as Zeno Clash) require Steam?
Because I think thats the only drawback for me.
The engine is a pretty good all rounder, and seems to be quite easy for people to work with, which helps a lot for modders and such.
manatree: Aw. Drawback. :( Anyways, DON'T TAKE MY WORD FOR IT, but I don't think so, because it's being sold at Direct2Drive.
No, you get a key that you register on Steam.
Navagon: Whatever else you want to say about Left 4 Dead, it's hard to deny that it made the Source engine show its age. For a horror themed game you'd expect the atmosphere to be one of the most polished aspects of the graphics. Yet atmospheric effects such as smoke, fire and even lighting were really looking quite antiquated.
Metro09: To an extent, yes. However, consider that L4D is meant to have more of a parody/cheesy B movie genre feel rather than true horror a la Killing Floor or Doom 3.
Especially the names of the different campaigns, they really lend itself to cheesyness. Still, that's no excuse for rather subpar visuals (well... then again, it was at night...). Getting L4D2 though.