I seems like it would be easy enough to make a counter-strike style mod for this game. You already have buy zones and buy time. Seems like you just need a level designed for it and a team deathmatch style mode.
Most people prefer very simple games where they don't have to get into it and learn game mechanics. Thats why Consoles are so damn successful, just because people don't want to learn how to use things, they just want to use them.
Don't get me wrong, I really enjoyed the game mode of CS and CS itself, but Valve made it worse and worse with every single version. Back then in the early Betas (6.X) until 1.4 I was a big fan of CS but more and more cheaters, flamers, weird bugs, douchebags, whatever showed up and made me search for something more complex. It's just like what they did with DoD, goddamn it's unbelieveable how great it was and how lame it is now.
There is enemy NPC in the SDK that include soldiers. your probably right on making a easy deathmatch style game. Personally I would like to see a squad of 3v3vzombies. Were your goal is to say destroy something each team is guarding why acorse having clots,gores,and others running around as well