Very cool theme! The time changes work really well here for your idea. The only thing that feels a bit off for me is the mixing, it makes some instruments too quiet, mainly the bassline. But other than that is a very well made song, good job!
I agree with you. I try some bass but it was to muddy with the timpani (EQ problem). So I went without it. It definitively misses something.
Thank you for your constructive feedback :)