Completing level 20 pops up the message "Game Complete", but going back to the main menu, level 20 doesn't have a star in the top left indicating that it's completed.

I've beaten the game, and all 5 achievements are shown as unlocked locally. However, it does not show up in my list of perfect games, Gravity Snake does not appear when I look at my achievement showcase, and sorting my library by achievement % shows Gravity Snake as "No Achievements". I've tried reinstalling and replaying the last level with no luck...

https://youtu.be/kDhTam41-HA

Teach me

It was an easy and fun puzzle experience. :)