Hi there, I just played Pythetron after I saw your (really impressing!) trailer and wanted to give some feedback.
What I liked is the overall presentation, the visuals, especlially the menus and shop, are great.
After playing the first level I was somehow disappointed, but didn´t quite know why, it did not feel as I expected from the trailer (and menu).
I thought about it a bit more, and I think what I really missed was much, much more enemies, there merely was somethink to shoot. Also, the weapons and explosions sound to harmless and some bonus-item sounds reminded me more of tablet-games like candy-crush. Especially the level-end sound and wobbly "bonus coins"-sign increase this impression.
Further, the ship overheats too fast, Jets´n´Guns for example had this feature balanced really well in comparison. And while shooting my ship is reduced to a bright glowing mass due some shading effects
The physics-parts feeled a litte alien and pointless for me, but that may be my personal taste.
Overall very interesting and a lot of potential, good luck!
PS: I also develop a (much smaller) Shmup, if you want to have a look: http://www.nemmelheim.de/trsgames/