The Last Sorceror

From Terrapod Games:

You stand in the middle of a vast open space. Hordes of ugly, violent creatures swarm towards you. You're in luck. This isn't the rush hour on the London Underground, it's Gauntlet-like game "The Last Sorceror". A lot more fun - you can't blast commuters to smithereens with nothing but your own willpower, however much you try. Your objective in TLS is simple. Stop the demons by destroying their entry points into each world. You need to find these points first, by searching for evil artifacts which reveal them.

The fun part is on the way, as you are attacked by and dispatch ridiculous numbers of demons. Your basic weapon, a magical arrow, is sufficient to turn a demon into a pile of dismembered limbs, and many more spells are found on the way.