Recently into Open Beta, The Mighty Quest for Epic Loot is a mixture of Dungeon Keeper and Diablo, where you both build a castle full of traps and monsters and attack those of other players in order to steal their belongings.
When you first connect, you get to choose one of three characters to play (a fourth one is available if you purchase a special pack): Blackeye Bogwart (The Archer), Sir Painhammer (The Knight), and The Earl of Evilosity (The Mage). Each has 3 different skill sets that you can mix to create your playstyle, and then everything else is defined by gear.
Once the character is chosen, you build your first -and modest- castle, by choosing different rooms to attach to each other (though there are two basic rooms -entrance and boss/treasure- that must always be included) and then fill them with various kinds of creatures and traps. You have a "defense rating" which limits the amount of challenges your castle can have, which can be increased by upgrading the castle (which also gives you access to new types of monsters/traps, new types of rooms, new items for your character, etc).
In order to build and improve your castle, you need Gold and Life Force; you get some of it from mines you build inside your castle, but for the most part you need to attack other people's lairs to get it. Part of the loot is generated by monsters/traps you defeat (which cost the defending player nothing), and another part comes from the owner's personal coffers (though these can only be plundered every 8 hours). In addition, conquering a castle takes Crowns from the defender and gives them to you. I'm still not completely sure what are Crowns for, but they seem to determine your ranking. You lose Crowns if you get killed at a castle or if your own castle is conquered.
Note that you don't have to actually be there to defend; attacks happen on their own and then you are informed when a player is succesful/gets defeated. However, before your castle's defenses can be tested, you need to be able to defeat them yourself, in what's called a Validation; if you fail to validate your castle, then your latest changes won't be encountered by other players. Validation also sets the "Target Timer" for your castle: If you take 3 minutes to finish it, then other players get extra Crowns from you if they beat it in less than 3 minutes.
The game has a decidedly humorous tone (it takes place in the Realm of Opulencia -though the technical terms used by Opulencians to refer to their country is "Prestige Feudal Heroism Community"-, where a real-state crisis forced people to take their castles into the sky, and where everyone constantly steals from everyone else, keeping the tiny sky-nation in perpetual conflict.
So far I've been having a blast playing it. The graphics are quite nice, the music is excellent, and the pace is frantic.
You can get is for free on Steam or UPlay.