Why did you decide to keep out the ambient pad in the second half of the theme?
Typically I feel pads come in towards the end of a song to give it a more grandiose epic feel towards the end. But I made this song a while ago and I think the idea was to have something relatively simple to play in the background over menus and stuff, nothing assaulting the ears too much, but I believe that i kept them out to highlight the C64 synth a little more. But I can always go back to it, I realize now its a little repetitive and simple, probably too long also.
I dont think being repetitive and simple would matter in this case. If this is the ambient and intention you had in mind I think it works ok for a game of this kind. Anyways you could try to put some little decoration here and there, but I'm not sure. Is difficult to judge for me.
Maybe someone else gives his 2 cents?