Team Fortress 2 is the sequel to the game that put class-based, multiplayer team warfare on the map. It delivers new gametypes, a signature art style powered by Valve's next generation animation technology, persistent player statistics, and more.
Dunno what else to say.
This happens to me when the enemy team has less than 2 heavies.
But the other team had like 4 heavies. My team had 3 - I was one of them.
This too.