For it being an older piece of yours, the mastering is relatively flawless. The drums are have a tad bit of static to em (not sure if this was intentional or not), and the electronic sounds are relatively fresh. If this were to have a few more "lines" added to it, pretty sure you'd have a front paged piece here. I'd go as far as to throw in some of the classic 8/16 bit sfx you'd find in classic platformer side scrolling shoot em up's...not gonna name any game names here, but IM SURE...you'd know instantly which ones I speak of.
4.5 to you! KEEP at it!