I like the variety or the things you can mine. (Minerals, crystals, archeological artifacts, gases, ect...)
The graphics are very nice and despite the worlds being fairly desolate (that I've seen), the whole thing is very graphically appealing.
The geology seems on par and some research seems to have been put into it though I am far from an expert on this.
The story really has that "lost, alone, and trying to find a way home" feel I think you may have been going for.
The music is nice and adds into the whole theme well (except maybe the more urgent aboriginal drum background song, it felt out of place after all the others, sort of like the background music off Halo:Reach during either "Winter Contingency" or the intro to "Sword Base").
1. The heat system, while realistic, was irritating at times. I wouldn't say "get rid of it" but making it a little less of a hassle or having a casual mode where I don't have to deal with the thing would be nice.
2. The lack of climbing ability. Seriously, this is one of the first things you would put on a robot designed to drill holes. Instead of using massive amounts of fuel to boost around (which is expensive and inefficient tbh), they would throw some strong brace arms that could climb around and hold it in place while it gets at mineral deposits. To late to do much about it now I believe, but it is something I dislike none the less.
3. The boosting inconsistency. While true this adds an element of strategy to the game, the fact that it can put out enough thrust to go a ways up but somehow can't keep doing this with the remaining (more than enough) fuel. It doesn't appear to be due to heating problems and it isn't really much to do with fuel (on account of the fact that it can still "glide" for a while and can do the same boost once it lands) and if you hold space it can somehow keep the bot pinned against the roof while it drills up, only stopping when it cant drill anymore (you could say that the drill is pulling it up as well but it's still if-y to me).
Some of the animation work is off and could use tweaking. The first jump is instant but it shows the bot readying for the jump and then acting as if it is jumping after it already having a good second of air time. I would suggest either putting a delay on the jump so that the jump is synchronized as it springs up or altering the animation so that it doesn't take that second to crouch down and then jump. I would also add alternate drilling animations for drilling sideways while mid-air.
I would type more but the things that I know I'll think of later aren't coming to me right now so I'll just post this and hope they aren't to important.