Pretty nice little demo! The side effects were a pretty clever implementation of the theme, though the screen glitch when getting hit was a bit excessive (fortunately, it seemed to turn itself off after getting the AI update).
The basic pistol was quite satisfying to shoot and I liked the feeling of making it more powerful with upgrades. I don't know if it was intended falloff from the bullets or just the pistol being inaccurate, but the enemies often spawned so far away that I couldn't seem to be able to hit them, yet their projectiles had no trouble reaching me. Also, some of the waves seemed a bit excessive and some of the enemies were really bullet spongy.
The level design and graphics were pretty basic, but had a few interesting moments. Unfortunately, it was very hard for me to navigate the level and I gave up some time after beating the first boss and finding the carbine. I kinda wish that instead of moving the platforms around freely, they simply moved along predetermined paths, and that it was clearly shown where each platform is able to go. Having to stand under cranes to attach to them was also a bit counterintuitive at first, since I expected to be able to latch on to them by aiming at them.
Still, good job getting the demo out!