I did conclude my Bydo game (for now), but I did play Final for a little while longer...

I played with the R13T on a lower difficulty for a while to see if it would unlock anything, and indeed it unlocked the R13A. It still doesn't seem as powerful as the ship from Delta, but whatever.

What was REALLY cool was that after I earned that ship and selected to play as it, there were some more new stages. The new final stage was like the first stage of the game, but now apparently you're playing as a bydo ship (unique to that mission?) fighting the humans and their R9 fleet. To tell the truth, I thought that seemed like a pretty cool stage, even on the lower difficulty level. I also unlocked some other ships, which are apparently based on Bydo biology. The only one I've tried so far has, for a Force, a miniature version of the Delta testicle/ovum final boss. And it shoots sperm, too.
I LOOOOOOVE Flying Omelette!!
Crawl and 1000