I see a lot of wrong answers here
a) DRM protection: Games that will only run when a certain key is entered (it can be bypassed with enough time and effort) and games that will only run when launched through a service like steam.
b) Connection requirement (for online games): If the client appears to be modified in anyway then refuse all requests for a connection to game servers.
DRM protection can be byepassed, that’s why you can find pirated copies of almost all games
DRM free games like GOG-games can be shared just by sending the installer to someone else, even though it’s not ethical to do so
Latest Answers