years ago, I pirated a copy of Half Life. It had what I could only assume was a way to detect cracked versions. Remember the long train ride at the beginning? That goes into the canyon and finally stops at the train platform with the guard standing outside? The guard that then has to open the door? In the version that I found, the guard didn't open the door. The guard fell over dead.

I tried again and again and the guard would still fall over dead every time. Wasn't sure if I was going crazy, or if I had just been trolled by a game developer somehow.