but you can't play non-steam HL or CS 1.5 online LEGALLY. Cracking software is illegal, there is a DMCA in the US which made it illegal in spite of you modified the software or not. (Note: it's just "illegal", I didn't say it's immoral or not

)
...and that's exactly what digital restrictions (or "rights" as they like to say, but the first one is more accurate) are for.