How is TF2 ridiculously complex? -Scouts constantly have to be on the move in order to evade and be a harder target to hit. They're the fastest class in the game, and they have a shotgun. Sounds easy, right? Hardly. Try moving fast while landing several consecutive scattershots on point; even professionals occasionally screw this up. -Soldiers are versatile beyond measure. Your launcher can let you trade health for mobility, and your secondary item defines whether you should be protecting your medic or bombing the enemy's. Soldiers need to be very precise with their jumping in order to make it in comp, because landing in front of the enemy medic as opposed to the enemy scout can make all the difference. -Pyros are interesting because they have weapons designed for noobs, but they have combos only pros use where they constantly swap weapons. For instance they can set a target on fire with a desgreaser, quickly swap to a flare gun/axtinguisher and finish them off that way. It's a win-or-die combo that takes a while to nail down. On top of that pyros can reflect explosives; more if they're quick enough. -Demomen are support players that are near worthless alone and invaluable in a team. Their sticky launcher can help them move around faster in exchange for health, and they can heavily damage entire squads of players with ease. However, predicting a single opponent's movements and walling him in with sticky bombs can be a tough feat. -Heavies have a spray-and-pray weapon. Not very interesting, huh? Heavies ultimately need game sense over anything to succeed. Where to ambush, which flanks are exposed, and how to act when he is and isn't backed up by his team. His most limited asset is attention; because his combat style forces him to belt down and look one way. -Engis are more focused on metagame knowledge. Where to place buildings so they're useful but also difficult to reach by the enemy team. A well-supported sentry gun in the right place can turn a solid defense into an imprenetrable one. -Medics don't really need to know how to shoot, though their inferior weaponry can be used to get out of some sticky situations. Much like the heavy their prime asset is game sense. Checking their back, when to pop an uber off, who to heal and when. Assaults tend to go a lot more smoothly when half of your team is sitting on loads of temporary hitpoints. -Snipers are often useless and plentiful in pubs. Professional snipers, however, can frag half the enemy team in a matter of seconds if the enemy doesn't pay him any mind. You have to nail targets in the head, and the pressure to pull that off consistently often makes it more trouble than it worth. -A godly spy is the most rage-inducing thing in the world. The right man in the wrong place can make all the difference, and the best spies can easily figure who is unguarded on the enemy team. It becomes a question of whether the spy should get a single critical pick messily and die immediately afterwards, or take safer picks and make the enemy team paranoid.