Absolutely. Although, that tends to work in multiplayer games. What you need in a single-player game are bosses and armies that require different tactics or spells to defeat. For example, have fire elementals and ice giants in the game. Wizards require both the fireball spell and the ice-bolt spell to kill them all. Warriors require ranged weapons for the elementals and heavy melee weapons for the giants. Thieves can't sneak past the fire elementals (because they emit light), so they have to find another way through, but they can sneak through the heavily guarded ice giant halls.
Thoughs?
