I'd like to expand the building aspect of career mode. You can build an infrastructure (walls, elevators, tracks) to help get in and out of the mine faster. I'm also looking into ways I can change the behavior of cave-ins for career mode to make them less frequent but more devastating.
A preview of the HUD that will be displayed when you've purchased the builder's kit in career mode:

Mine carts!

(drop a bomb behind the cart to make them go really fast!)
I've also added some more minor features. Pressing N will toggle the display of player names. I've also made some maps reset. When you start a survival game the map will be restored to its initial conditions. Tunnels dug in previous games will not persist. I'm also working on saving and loading for career mode. At the very least your money and inventory will be saved, I'm not sure if I'll have map saving in place.
There's still a bug with avatars. If you've earned certain combinations of medals you'll unlock avatars. The bug is that you should be able to select your avatar at the main menu, but the game often fails to get your list of medals from the BYOND hub. This feature works all the time when I run the game locally, but when joining someone else's server I have never been given the option to select an avatar.