Interesting concept, but I'm getting this in the tutorial:

FATAL ERROR in
action number 1
of Step Event0
for object obj_enemy:

############################################################################################
VMError!! Occurred - Push :: Execution Error - Variable Get kills_in_sec
at gml_Script_enemy_update (line -1) - <unknown source line>

The light effects are awesome! And the backgrounds are minimalistic and original ; ) .. I was playing it some time, and i would love to have a Fullscreen version of it (My desktop wallpapper is very shiny and kind of distracting for a light based game..) Btw. i think i found a bug.. ; when you have lots of bullets to shoot and you attemp to shoot them all, the game crash.. Still i restarted the game and keep playing ; )