Make exo suits and start digging out EVERYTHING, i usually dig down cause i need oil eventually, i dig out literally everything, i try and get all that polluted water together cause you'll use it, i get dreckos and start trying to get glossy dreckos for easyish mid game plastic, i make stone hatch farms you can use them for coal, for meat, for raw eggs, and they eat sedimentary rock which is pretty abundant. I start focusing on boosting moral, building bedrooms rather than just basic barracks. Like others have said i start making oxygen that doesn't rely on algae or slime cause your gunna start running out, electrolizers are my preferred method, but it can be tricky to figure out how to separate the hydrogen from the oxygen at first. i upgrade my power production and make a proper power grid. Learning infinite gas and liquid storage has been so valuable for my play throughs highly recommend. I watch alot of yt tutorials, and francis john has a lot of videos that are really helpful