Warhammer 40k: Space Marine is a single player game from Relic Entertainment. You play as Captain Titus and run around killing Orcs. One of your weapons is a Power Axe. This video shows you what a power axe does with some gruesome results. Oh, and you know, the technical details but mostly just killing.
Warhammer 40k: Space Marine will be out for Xbox 360, PlayStation 3, and PC on September 6th, 2011