While Klei has been busy expanding the Oxygen Not Included expansion Spaced Out, they've now come back to the main game to improve it for everyone.
A lot of the work on Spaced Out mechanically has improved the base game, with Klei mentioning that the two were actually on different codebases but that's no longer the case. They went back and unified them so that everyone who doesn't own the DLC can see some improvements. What the Breath Of Fresh Air update brings is a focus on some "long-term concerns" along with a new Modding API and an upgraded version of the Unity engine.
- New traits, including traits that grant skills to Duplicants right out of the printing pod
- Some shuffling of the tech tree, notably moving most of the Conveyor Rails techs one tier earlier
- Updated food storage mechanics, making refrigeration easier and more effective, but removing exploits and creating a natural progression for fully preserving food
- Meter Valves allow sending precise amounts of material down a pipe, manually or using automation
- Oxygen Masks are a new low-tier suit, allow Duplicants to work for longer in low-oxygen areas but not protecting them from harsh environments
- Suit durability mechanics will be available in the base game (off by default), which add some upkeep costs for suits so they aren't so overpowered
- "Stinging eyes" and related debuffs give more reason to be cautious with chlorine and other gasses and liquids
- The Diagnostics panel, updated Resource screen, and other UI improvements make it easier to stay on top of what's happening in the base
- Demolition skill allows duplicants to destroy those Gravitas ruins once and for all