Based on the first day on Early Access, here are the bug fixes:
1) Optimized for better framerates at default settings
2) Default settings button added
3) Difficulty adjuster tweaked
4) Dynamic Shadow option added for high/low res shadows
5) Demanding graphics options like Ambient Occlusion, Super Sampling and Dynamic Clouds are turned off by default. In house test is getting 95 frames on a GTX 980 ːsteamhappyː
More bug fixes coming next Monday.
IMPORTANT NOTICE: If you purchased the game on the first day, please hit "Reset to Default" option in the pause menu to apply new optimized settings for your PC.
Cheers