Many things have been added since the last release, so many we forget what exactly...
But you can expect new enemies, a new weapon (sword), HDR (your eyes should adjust to the darkness), and more... Rooms.
It also includes an early implementation of (single player only) Oculus Rift. Please see the official website, or the forum for more info.
Tomb of Rooms is currently free to play. If you support development (pay what you want), then you'll get all the new versions as soon as they are released.
To download, go here: