Yeah, the levels can be a little tricky, haha.
3rd level should be the spring level, right?
As for the thing you might've missed...
PUZZLE SPOILERS
The fuel hub has a little ring around the number indicator, that serves as a "cooldown indicator". You CAN double jump, but the jetpack has a "cooldown" to keep it from overheating.
Oh, didn't realise I can do this!
I gave it another try, because I wanted to see more of those "tricks" in level design. This time I made it to the end. I really liked the level with those radioactive balls that you have to avoid, that was quite clever. The two dark levels were fine, but I like my levels to be visible :D
All in all - a fun experience and thank you for taking time to respond with clarifications.
