TF2's gameplay also heavily emphasizes teamwork (it's in the name, after all), arguably more so than other class-based shooters. TF2's gameplay is rich with depth, more so than any other class-based shooter.
On top of these core principles, there are also tons of well-balanced weapon unlocks for each class that allow players to create loadouts that suit their personal playstyle. Soldier players can learn how to perform skillful rocket jumps that allow them to stay mobile and make the most of their splash damage Engineers need to read the battlefield and decide where to construct their buildings and when to retreat from an enemy push Spies have to figure out how to move behind enemy lines safely and then strike with a backstab or two when the time is right. The game's nine classes (Scout, Soldier, Pyro, Demoman, Heavy, Engineer, Medic, Sniper, and Spy) each have defined strengths and weaknesses, and the skill ceiling of learning how to maximize the former while minimizing the latter with movement, aim, and gamesense is near-infinite. The primary thing that keeps me and so many other players hooked on TF2 is its incredible gameplay depth.
