OK first things first - yes, there are a million of these 'style' maps available now but I believe mine is a little different. It's not just Freeman on Combine - it's Freeman on Combine, on Antlions, with Rebels! And its a 'sequel' to my HL1 map Allout (duh!) which was strangley popular considering how err.. 'unproffesional' it was.
New features include:
Combine & Antlion gates;
Kill-all switch (25 seconds to recharge)
You might want to set r_decals to something like 30 and r_drawflecks and r_drawmodeldecals to 0 for best performance.