I mean, where do I begin?
What an achievement to have made this game in mere 4 days. From the cute art and character design to the charming and very fitting music, this game brings you back to the glory days of PS2, when games where just made to be fun, and nothing else. Very well made game that keeps you wanting to stacc 'em all, while having a blast doing so.
Only suggestions that I can think of, would be to perhaps add some wind sounds when you are climbing the big skyscraper, to give you that sense of height. And a cool effect would also be to silence the music when you're standing at the top, to add to the climactic suspense of getting ready to do the longest jump in the game.
I almost feel bad giving you guys suggestions though, as you already did such a great job. This game is a serious contender for becoming at the very least a top 10 game if you ask me. Bravo!