Turning the platformer game into something of a puzzle could be an interesting idea. I think the presentation of the game could have benefitted from original characters rather than using Mario's though. In terms of design, making Mario slightly faster than Bowser would have allowed you to make better puzzles that require you to keep Mario at a distance to where he can't catch you throughout the entire level. I can just keep moving and Mario will never catch me with the speed the same as it is. The music doesn't fit the game at all and gets old fast. If it was something with a faster tempo to make it feel like a chase that would have been much better for the tone of the game. Coding wise it works alright, but there are a few bugs. One is that Bowser can get stuck in the walls since when he runs right you can see that there are a few pixels that can appear behind him in the animation allowing you to clip into the wall. The second is that if you run in any direction toward a wall, Mario can never reach you. He just stops. Not entirely game-breaking as once you move you're generally dead, but still.
Don't be afraid to take risks and get more creative in your design. It will make you need to think outside of the box for your code and the game much more interesting for players. Keep going, my friend.