Nvm. Needed slightly more speed on earth. use M3-IF bottom, M5-AH Cockpit, M5-A Fins, M5-F Main Boosters, M-5 Cockpit Boosters, and not too heavy slot items and it unlocks no problem
I wouldn't say tedious. And the one solution makes it a bit more challenging. I enjoyed it. On the other hand, the thinking is pretty linear, so maybe two possible solutions for some puzzles would be nice? You'd have to be careful to keep the difficulty high enough, but it'd make it more interesting.