Yeah I really dig the oxygen rule! Oh now there is a oxygen room to replenish it nice, its not only the item. I would have ruled that if i get back to my ship I can replenish it. (Been playing some 'Deep sky derelicts' lately maybe thats where this comes from)
Cool new stuff! Already looking forward to the next game so i can check it out! As well to your upcoming ideas!
P.s.: the 2d6 mechanic for foes in comparison to dark forts only d6 is great, the chance of rolling a foe is higher than the other more scarse things