This was interesting! It took me a while to "get" as I didn't really connect that the star was exploding because of me/time, perhaps the "unlock next stage" upgrade could've been placed somewhere separately to make it stand out more. It was a bit odd that you had to go through all of the stages after each reset though. I would've thought each stage would be its own "layer" that you work on until you unlock the next one and start over with a new set of upgrades and resource. This way isn't bad necessarily, but after I figured that out, it was very quick for me to go from one star to the universe, and if I had a habitable planet right at the start, it meant that the game finished very quickly after unlocking the universe.
Mechanically speaking, I think the upgrades needed more separation, especially with how slow the scroll wheel works (dragging LMB is much faster, thankfully). Rather than keep each stage's upgrades all in the same column, I think tabs for each of the three sections would've made it much easier to understand what's going on. Also worth mentioning that the star collision SFX is very loud, even with SFX turned down to 10%, they might be overlapping for each star that collides?
But this was cool overall, hopefully you get some more plays now you've got a web build out (I doubt you'll get disqualified for that).