My terrible time management skills... and stress induced panic.
Like, my gamepage says I submitted it 26 minutes before the deadline, but it's really closer to 10. I just started setting up the page real quick first so I didn't have to think about it when I finally got the game completely finished. (Not that that helped at all since I forgot to turn on the move event that would have brought the player to the last section of the game.. TTATT)
Also battle balancing. Honestly the battles are a mess. Partly cause I had the "bright" idea of doing kinda custom classes and skills with way smaller numbers to make it easier to balance. And then bad time management happened cause I hate doing battle balancing so... Giant mess.