Great game and made by 1 person which is impressive. Like most people have said, it is difficult to play as one player but rated it as thou I had two players. One idea to help with this is two options, 1 player and two player mode. In the one player mode you could have some basic AI to control one player and have a button to swap player if you need too. This would keep the theme of feeling like 2D as you would flick between the two worlds. Love the concept thou and very fitting to the theme.