Thanks for sharing, I think your demo's pretty solid. Here's some feedback:
Controls, objectives, game mechanics and hazards are fairly clear and intuitive. I was able to figure out quite easily how to play and what I needed to do without reading the rules. (Of course, I think it's good you have rules to keep things clear or guide someone who's never played a runner game before.)
Reset time is good, it makes it easy to keep playing and not feel like there's a delay.
I think the sound effect for when you die is rather harsh, the reverberation is a bit strong and honestly it makes me feel pretty bad when I mess up. I would suggest toning it down a little.
The controls are very smooth and tight. The clean artwork and catchy music feel very polished, too.
I liked the bubbles a lot because I felt like I could slow down and plan my next move better. I'm not a huge fan of fast-paced runner games or games that are intentionally really difficult, so I like opportunities where I can take a step back and pace myself.
I hope this helps! Good luck with developing your game, I think it's looking good so far.