time, time and time :).
Player is meant to be a bit different to the enemies, simple thing of filling the centre when creating that shape, as well as being a triangle :P. Blury/softer is usually associated more friendly, than harsher/sharper (for the enemies). That was the minimum thought process I went through before moving onto other things, like creating the rest of the game :D.
Parallax or other background movement FX would have been nice - fell off the stretch goals list due to time.
Gamespeed, not sure which element you mean by that in this case. Speed of enemies ramping up,.. getting upgraded faster,.. etc. I did spend time balancing things so that even though it felt slow to begin with, you soon ramped up move speed and fire speed, and felt that progression and change and improvement.
Health bars (or such) for enemies, would have been nice - same as before, time constraint.
Menu improvements,.. pause menu, more detailed Sound control, credits screen, in game controls etc,.. all nice,.. but again, no time :).
My time got taken up on making the game itself, and trying to make it feel tight for what it is.
thanks for the feedback though, all things to consider for any future progression.