DotA was the game where you there were two big NPC bases on opposite corners of the map, and NPC units were constantly spawned in waves and sent towards the opposing base. if all the players stayed to the side then there would be pretty much a perfect equilibrium between the two bases. The players each controlled a single hero unit, which leveled up and bought items over the course of the game, and helped the NPC waves push their way to the enemy base.