Update 7 is now live!
Biggest change we've made is adding Steam workshop support. You can now save to workshop directly from any of the Sandbox levels.
http://steamcommunity.com/app/287220/workshop/

We've completely redone the UI. Way better menus, load / save screens, inventory, etc - and a new help screen

Besides the UI and Steam interpretation, we've been changing a lot of the game's engine to prepare it for our future plans. We are hoping our next update will include online support, which is still in development.

Other changes include:
- After reading community feedback, we decided to open up all Sandbox items. No unlocking process anymore
- A number of avatar mode fixes, now default in Sandbox. Now same scale as before. Character now goes into ragdoll for crash, then gets up on hitting Enter
- 'Featured' offline creations in Sandbox mode, replacing the old online system
- 10 new parts to build with
- New particle effects
- More graphic options in menu
- UI Sounds