I finally did it - 3.17. Without any death or error on the way. Those guys who say that you shouldn't try to get checkpoints are right! Just keep running as fast as you can.
Niknod, thank you for your comment. I really see some mistakes I made in this game, but the jumps limit is definitely not one of them. The game is short and requires luck, but the proper order of upgrades and knowing, when to use active skills make it so much easier to at least upgrade all to maximum.
Thank you all for playing, I will do my best to make next game more playable and fun!
There is plenty of games, where you have unlimited jumps/days to achieve maximum upgrades. Turtle Dreams to Fly gives you a challenge, where you should find the best order of upgrades to achieve best results.
 "Danger Dungeon"){kind=icon}
 "Pursuit of hat"){kind=icon}
 "Katwalk"){kind=icon}
 "Absorption"){kind=icon}
 "XenoSquad"){kind=icon}
 "Think Tanks"){kind=icon}
 "Diamond Hollow II"){kind=icon}
 "Frantic Frigates"){kind=icon}
 "Turtle Dreams to Fly"){kind=icon}
It saves after each level. Just updated game, with API integrated.