Took a while to stop getting aggravating and start really enjoying this, but once past that point it started getting pretty addicting! A couple of runs through and I finally have all medals and at least a couple highscores. One annoying thing though: when you complete all challenges, there's no way to submit your final score, or to (I assume) double the final challenge awards with a ruby. Also wish there was a built-in re-check for medals you may have attained, so even if the system glitches you can unlock ones you've missed. Seems like a suitable place for this would be the final 'you'ce completed all challenges' screen. Also wish scores were posted automatically, since it's easy to forget to press that button in between runs.
Overall: great game. Both upgrades and obstacles feel balanced, the pixel graphics polished and nostalgic, the music catchy albeit when things don't go too well somewhat annoyingly uplifting. Easy to get started with, and play again and again, and find patterns to the more you play. An awarding challenge!
Wonder about the savefile for this game btw: where it might be located? Is it local?