Very cool platformer, rather lengthy for the time constraints too! I also loved that there were secret passages, it is a cool feature.
The music was nice and the shot/reload sounds were on point. I'd have enjoyed some more oomph for when the player dies, and perhaps the spikes/saws could also have some sound indicating they are close by.
Visually it was very cohese. I just found the tutorial inputs at the beginning a tad confusing. There were also some artifacts in the platform tiles, as if the tilemap wasn't really fit. But maybe that's just WebGL shenanigans.
The double jump could have been easier to execute, I just discovered it because I kept on pressing space desperatly at the first wall I had to jump. It seems counterintuitive to not double jump when at the top height of the first jump.
There was a point in the map with a lower platform underwater, that had a secret passage through the wall. While walking through it the screen transitioned to show underneath, the transition could have been smoother, felt like going into another different place.
It took me a while to understand I could shot downwards to move up, but it was fun once I got it. Some nice platforming and spike avoiding challenges you got there!
It's also really amazing that you got achievements and a leaderboard, very, very well done there!
All in all, congratulations, I had fun with it once I got the hang of the movement!