It's an overall good mining game. Changing from currency to recipe is an interesting idea, but would be better if the recipe tree isn't nested so _insanely_ deep (almost every blasted thing needed bolts/screws... but so did their other components - it would have been less grief to just cost an extra component or something). Allowing us to convert between different grades of ore saved a ton of grief, and I think you for that. Navigating the recipes was nicely done, but including an indicator of how many more screws are needed for the currently desired upgrades would save a lot of grief. The deeply nested recipe list wouldn't be much of a problem if we had an overabundance of resources to work with... but we can't afford 500 screws usually. Making screws 1-5 at a time as necessary just takes _forever_......
Finding the artifacts in a random order is reasonable, but it seems very odd that the data logs (which are assumed to be made by you) are not chronological. If you find the items in a different order, the logs should indicate that.
Losing the ability to fly was somewhat annoying, but it did cause us to develop new strategies to cope with it. Lava was an interesting innovation, but they were too annoying to empty.
The "reduce vibrations" upgrade seemed pretty worthless. It only makes getting the fragile egg thing easier, but the strange gloop it contained was worthless. I don't think there was a single recipe that made use of the strange gloop. Fortunately, it didn't seem to make emptying lava pockets noticeably harder.
1) This isn't motherload - digging as deep as possible as fast as possible will fail utterly. Almost all upgrades require special items that cannot be made before the recipe is discovered. Therefore, it will be near impossible to dig very deep. Starting strategy is to find artifact, find new planet, repeat until all artifacts at that depth have been found. There's almost always a shallow artifact slightly to the left of the starting position.
2) Because your digging capability is limited largely by heat, start with temperate/glacial. Many things only appear at certain depths - eg if you can dig to 200 on a glacial world, you may find 5-10 Ti per map; if you can only dig to 100 on volcanic worlds, you'll find 0 Ti even if the planet says "300%"
3) Upgrade costs escalate towards the end. My excel spreadsheet says that upgrading everything from 4->5 (except drill vibration) costs the equivalent of (all at the lowest grade) 880 Azurite, 826 Amethyst, 853 Emerald, 880 Ruby, 1160 Iron, 432 lava (and less crazy amounts of the other items). To save yourselves some grief, make 127 screws, 55 bolts, and 58 wireless wires. I don't want to flood this box with a complete spreadsheet, so you'll have to figure out the rest yourself, but hopefully that's a good start. (remember that this list doesn't include any of the previous upgrades!)