After being a mod for Half Life Counter Strike became its own game. Counter Strike: Global Offensive or CS:GO is the top Esports shooter.

Team Fortress 2 is a classed based first person shooter. It comes with many gamemodes I would recommend this to someone who likes fast paced shooters

Garry's Mod was originally a mod for Half Life 2 but it was made into its own game! It has great gamemodes which makes for hours and hours of playtime

At 1st its a platformer. Then you reach level 3 and you go to the website and report game is bugged and can't be finished! Very hard game.