Just got it to the end finally, got the achievement, and the little extra bit after the credits was hilarious! 
Did have some issues with the reactor core though, when I’d toss it through the portal to the next platform, it could still roll around on the platform, but I couldn’t pick it up. I had to shoot it a few times til it popped up into the air and I could grab it again.
Also, the reactor core was annoying in general because if you got too close to the back wall you’d randomly get killed. So fun. :what:
Oh, and the end portal raped my frame rate. I was pretty good all game and then BAM, down to like 4fps.
Now I’ll just have to do it all over when this gets on Steam. Oh god. Hahaha
Edit: And I was meaning to ask what the hat meant, but then randomly stumbled across the answer on Facebook. lol