This game screams early 90's arcade shooter / platformer, awesome!
Going straight to my favorites in fact.
As demicrown mentioned, it's reminiscent of Rolling Thunder, and perhaps a bit of the Elevator Action sequel. Good stuff.
I did find a little glitch when as soon as you fire when crouching, and immediately press the opposite direction, the bullet and bullets you fire afterward project behind you. It's even more fun to do whilst standing because Agent Ruby does a little Gumby slide afterward ;D
Anyway, this is a great game, and I hope you decide to make a sequel down the road.
Keep up the great work!