Recs.
Updated
Team Fortress 2 is a multi-platform, first-person shooter, multiplayer game that focuses on team based gameplay, where each player has their own unique role on the team.
SpecsUpdate
Pros
Pro Engaged, active, fun, and creative community give the game a welcoming feel, even for outsiders
The TF2 community is know for actively engaging in different TF2 related activities. They create shorts using the source filmmaker, sell items via the steam workshop, build real-life sculptures, etc.
Pro Hectic FPS gameplay that utilizes 9 distinct classes, each with lots of varied items
TF2 has 9 playable classes - Scout, Soldier, Pyro, Demoman, Heavy, Engineer, Medic, Sniper and Spy. This allows for a range of playstyles. For example, the Heavy, starting with 300 health (going up to 450), wielding a machine gun and usually assisted by a Medic, will be commonly found on the front-lines soaking up lots of damage and pulling the enemy team's focus; at the same time the Engineer will try and avoid direct battle as much as possible, providing infrastructure (teleports, sentry, dispensers). Add to this hundreds of weapons for each class providing different stats and you have an impressive amount of variety in gameplay.
Pro Tons to do in the game with plenty of game modes and plenty of community mods
TF2 has more than 10 game modes, plus variations on those, as well as community mods that offer a wide range of objective-based play. Classic game modes include Capture the Flag, Control Point, King of the Hill and Payload. There's also Mann vs. Machine, a co-operative game mode where you play against waves of AI controlled enemies.
Pro Fun and humorous gameplay with graphics and sound that fit with this theme
This game has a history of over-the-top characters, visuals, voice-overs, and various other items, which altogether create an amusing world both within the game and outside of it as well. You get a feeling a lot of thought has gone into the development of the characters as well as the world they live in. For a genre that is often filled with drab characters in a drab world, it is refreshing to see something so well fleshed out.
Cons
Con Random critical hits add a significant luck element into the game and push certain types of players out
In most 'public' servers, an option called 'random crits' (short for 'random critical hits') exists by default. This allows a random percentage of your shots to multiply damage by 3 for a shot, and also remove the damage drop-off over range. This 'feature' gets increasingly more annoying as you get more experienced, as you will die more often than your opponent having x3 or more damage over you, actively making their experiences and wins less meaningful. Some classes are especially burnt by this. Medics don't use weapons often, Snipers only have secondary weapons and melees, and Spies only have their revolver (and most sidegrades of that revolver remove this ability entirely). Quickplay (a feature most newbies use to get a match) also disables these servers from appearing in the list, so there are very few 'nocrit' servers because many don't know they exist.