system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do games know if its been pirated or not? How do game developers code in a repercussion to pirating a game?
gpt
It's possible for a game to connect to an activation server and check the key used to activate the game, and if it is blacklisted on the server, it may be a pirated copy.   Most cracks will try to disable this.   

In some notable cases, the developer released a cracked copy of the game intentionally, but with a few subtle modifications that would ruin the experience for pirated copies.