I've started working on the round based section of the game (known as The Depths) to give myself a break from the other stuff. The Depths is a round based part of the game accessible at any time, which gets progressively more difficult as the player fights through each "floor".
Each floor consists of 8 time constrained (1 minute) rounds and a final boss; once the player has defeated the final boss of the floor, the plug at the centre of the room is destroyed, allowing the player to jump down to the next floor.
<img src="http://i.imgur.com/Wsfdm.png" border="0" />