This was an enjoyable and simple game. The Movement controls were a bit too unresponsive, even during untouchable mode, which made certain points unnecessarily harder than they were likely intended to be. The basic weapon is perfect for it's purpose and fires and aims well, although it only just holds up, up to Skynet levels. Beyond that, even it's tier 3 shotgun effect is almost useless.
I did enjoy the fact that the second weapon option was unlocked well before the end of the game, and it encouraged me to continue playing even after I had died thrice with the basic weapon. However, despite there still being some challenge to the game using the seekers, it did feel a touch over powered at times, and i found myself wanting for a middle ground weapon.
The Variety of Foes was pleasant and diverse enough for the length of the game, and i did not at any point feel bored with any individual foe type. Had the game had another set of levels however beyond the final boss, the older foes would have started to feel dated.
Beyond that, my only complaint is a personal one in that the background/setting got rather tiresome after awhile.
If you make a sequel, I would suggest greater variety of enemies, more weapon options that are varied and distinguished, and a change of local or appearance there of. Some more creative Enemy fire would be a good idea also, Like Shots that turn 90 degree's after x distance, or lasers that rebound at set travel distances rather than just off of walls.