When the game first came to steam back in may 2013, there were only 3 different rooms to build, the ui buttons didn't work, mouse-wheel scrolling was broken, the ai was terrible, and there were no sound effects.
As of early December, there are 8 rooms, the ui is fixed, scrolling feels normal, the ai is better, and the sound effects are great. -Not to mention they went back and remodeled a character because of negitive fan feedback. It's good to see this game taking shape.
As for the gameplay? Well, Peter Molyneux declared it the spiritual successor to the Dungeon Keeper franchise, so there's that. It's a basic sandbox dungeon stratagy game that requires you to build an underground lair, collect resources, train minions, and defeat your enemy. Along the way you can build traps and defenses for your dungeon, cast various spells, and spend xp on 3 different skill trees.
EA killed Bullfrog 12 years ago, so go spend $20 and pick up a copy you cheap ♥♥♥♥♥♥♥s.