The Resistance in HL2 NEVER EVER goes out and does something open. They would be killed instantly. What the rebels do in HL2 is give civvies food, books, and other things to help them survive. Giving them guns and going out on a war with the combine would be suicidal. Same applies here. If you want to be a rebel, you can, but that is what you should be doing. Passive stuff. Not killing a lone officer, taking his gun and staging a massive assault, as COTA will be called in and you will be bitch-slapped.