Fun game. I had no frame rate issues compared to what others are reporting here. It froze momentarily a few times when I got to a new area for the first time, but I figured it was just loading.
--spoilers ahead--
The one thing that I both enjoyed and was a bit disappointed with was the fact you could rocket jump after getting to rocket launcher. All sense of level design is destroyed after you learn this and can practically bypass any obstacle with it (I even managed to reach the end of the game before getting the flame sphere). Speaking of the end of the game, when I first got there without the final weapon collected, I didn't even realize there was an entry point to load a new scene at the doorway to the bio dome. The rest of the dome can just be walked through so I thought the ending was literally just the last entry on top of the mountain since it felt like the dev wasn't expecting players to continue past that.
However, it's a good thing I went back through all the areas to explore and find any missed entry logs (including the one is out of reach without rocket jumping, and find the flame sphere), because I went back up the mountain and accidentally stumbled into the loading zone for the final area.
The choice between fighting for the melon or traveling to another planet was interesting. Of course I chose to fight first.
The boss was cool (and might I mention all the bosses were neat although I wished they had some more varied attacks), although the final one was very easy after trying the fire sphere on her (which I sure am glad for because every other weapon did very little damage).
I liked the epilogue to wrap up what happens when you get back to earth, although it wasn't really clear who the 'kill gang' was or why they were barbarians with shotguns and axes. Maybe I missed something, but that part confused me.
The other ending was neat, although much less satisfying. You walk through the portal and then slowly walk to the city in the distance and then... credits roll. No epilogue, no nothing. So I guess stealing the melon and bringing about the end of earth is the true ending?
Anyways, I did really enjoy the game, I wouldn't have written out this entire thing if I didn't. I hope the dev continues to work on bigger and better games. It was fun to explore the alien world of Xanadu