This is a map I made after playing a Helm's Deep map for Counter-Strike. As far as looks go, I based on pretty much entirely on the CS map (which was pretty accurate as far as I know). In terms of gameplay, don't expect the marines to kill everything for you, you still have a lot of killing to do yourself. Also, the level will slow down at a few points, so be warned. If you have a lower end machine it may beg for mercy if you try and play this.
Uhh, like a week or two.
WadAuthor, Warm, Wintex, PSP, various text editors
Don't kill the green demon, though it's not possible without a projectile weapon which you won't have at that point. Like I said, the map will slow down at a few points. I've done my best to make it playable most of the time, but your results will vary.