No story, no tutorial, but just plain fun!
Demigod takes place in an arena: think Unreal Tournament, but the twist is that you control only some (or one) of the units on the map. Portals spawn creeps that fight for either your side or the opposing team. This adds an interesting tactical complexity to the game: you can capture portals to add to your fighting power. At the same time you need to capture flags to gain special advantages (like more damage for you team or more mana) and to increase your war rank. Increasing your war rank unlocks essential upgrades that you can purchase at your citadel (main base).
Overall the demigods are balanced as demonstrated by Stardocks own win/death stats.
Demigod is a unique and interesting game well worth your money.