I like the mechanics of the game. I think there's a lot of potential for speedruns. Somewhere, it should be described that you can right-click or esc to get out of a planet. Also, it sometimes glitches when you try to click on a planet, it picks up a person instead for some strange reason. My least favorite mechanic is having to pick up people manually, maybe when a planet reaches population cap the people get harvested automatically.
Despite these minor suggestions I made, I want to stress that I really like the core concept of balancing O2 and heat and I love the added twist of elliptical planetary orbits to make the heat balancing more difficult.