lol,
well i am actually quite interested in coding this game for real. And its not using any STEAM or HL code at all. AND, instead of using own-made gfx (which is couragious though!) , i use(d) wally to extract textures. It really looks like CS like you know it. Although i have just started yesterday, i will keep you guys informed.
My plan is, get a map scroller first. Then do some nav + collision detection. When that is done, the fancy gfx stuff (lightning, shadows, FOV) will be in.
The downside of 2D is like Trub said, you cannot view to much of the screen; yet, thats also what makes it so fun to play
For now the resolution is 640x480, but i want to up that to 1024x768, because tiles of 32x32 eat up a lot of space (especially when you have crates of a size of 64x64)