In the 90’s, iD made Doom, made money off of it for a few years, and then released the source code. They then did the same with Quake. This is part of the reaso

In the 90’s, iD made Doom, made money off of it for a few years, and then released the source code. They then did the same with Quake. This is part of the reason companies like Valve exist today, as their early games used modified engines from Doom and Quake. Valve is now continuing that 25+ year tradition. People are still making new Doom maps and playing the game. If history is anything to go by, people could be playing TF2 in some form in the 2050’s and beyond.