Oh wow. Crazy. So, I guess I could try with another game. I have:I actually don't know because I bought mine (along with every other Half-Life game, mod, etc.) for like 20$ during one of the Summer sales. I didn't have key for my CD copy because it was pirated copy I got from my brother and it came with a keygen on the disk itself.
American Truck Sim
Emily is Away Too
Defend The Highlands
GMod
Undertale
Bad Rats (How do I get rid of this? XD)
Plague Inc. Evolved