The first levels are very frustrating. The short timer and some of the hidden traps (which you can only detect by failure) make it hard to like the game initially.

Also, it is not immediatly clear that you have to stand on the exact position of the green flag. On the first to levels I was just running through the flag, and that was accepted. On the third I got frustrated because it didn't register me hitting the flag when I passed it.

However, once I got the hang of it, it was quite fun to overcome the obstacles, and I like it a lot.

I think the game would benefit a lot from a short introduction screen. Just single screenshot saying that you have to stand exactly on the flag when the timer runs out, and that there can be hidden traps only detectable through trial and error.

I would assume the inspiration was from SMM levels. If not, then hey at least this is intriguing.

a decent platformer, though I can't help but think that the whole mirror concept doesn't add anything to gameplay and just slows progression

The concept is kind of interesting. It would be good to have an actual timer on screen. I think that would increase the tension.