This is a SPOILER since the final trailer will be better than this. If you want the real experience, than wait for the finished trailer. Otherwise go ahead:) Here is the list of things that will be added / changed:
- Background Music
- Sounds (furnace, assembling machine, pipes, boilers, inserters, biters, etc.) - might be integrated in the music
- Fix biters sliding and twitching when avoiding obstacles
- Install the new terrain and doo-dads