By taking a gander it seems like most people are only getting as far as completing the second or third level. Only 2 other people beside yourself have gotten the any of the secret medals. (The last 2 only acquired by yourself at this point). I still think this game could have used a stage select for completed levels, because having to replay everything when losing all your lives is more arduous than fun. I liked the level of challenge, but having to do everything over because of losing clearly doesn't compliment the game play. Imagine if they did that on Sonic Adventure 2 and you'd see it would be kind of annoying.
I thought you showed good level design by sort of trapping the player by the moves they made, especially in the mushroom kingdom level. It makes the player have to remember about those little "Gotcha" moments for next time, although getting killed by a "Gotcha" moment at a later level and having to restart everything is not very rewarding for the player and discourages them from investing more time into it.
The story was funny and cute, I definitely believe Waluigi would do something like this. I don't know why there needed to be an ominous villain but I guess that adds to the humor. Like I said I think you did a good job with this piece and the way you practiced new coding. It might be nice to see you working on coming up with your own mechanic and building a game around that in the future which is something I don't think I've seen you do.
Congrats on the daily 4th!