This is pretty much the purest form of the theme, no nonsense, there's a countdown, it's tiny, and you gotta finish before then. Using time as your life total's a cool way to make the countdown more interactive and relevant, which strengthens the theme more. And giving the option to skip levels is an accessibility option that you don't see often in game jams and it's appreciated since some of these levels are pretty tough!
I found myself mostly using the dash for attacking over the gun, but I like that there are clever design choices to force you to use the gun, like not being able to drop down through platforms (I think? I couldn't figure out how to, at least) meaning enemies in platform boxes essentially trap you if you dash up into them, meaning you have to use the gun to take em out.
One last thing, there's a bit of a funny bug where if you hit the flag as time runs out and the game's transitioning to the game over screen, you can start the next level with negative time, and it'll go on forever haha.