Ultratron
The last human is already dead, slain by evil killer robots! As the last remaining humanoid battle robot, you must avenge the human race and destroy the four bots of the Apocalypse. Pick up powerups on your way to help you out. Fast action retro arcade game based on Robotron. ... Play for hiscores and glory!
http://www.puppygames.net/downloads/SetupUltratronDemo.exe - 6Mb - Download - Screenshot

RetroBlast
Fast action retro vector style shoot-em-up in the style of Robotron meets Geometry Wars, with plenty of non stop excitement spread out over 100 levels. Several blasts from the past challenge stages where you can get bonus points and power ups. Very easy to use mouse controlled game play, online... Works great even on lower end computers.
http://jgofiles.com/download/retroblast.exe - 3Mb - Download - Screenshot

Roidulous
Roidulous is a retro style 2D arcade game based on the classic Asteroids. But it goes much further than just another asteroids clone. You get massive amounts of stuff to shoot at and destroy. Plenty of eye candy, explosions, powerups, new weapons, etc! ... Because the action is so frantic it's kind of like Robotron meets Asteroids. ... If you enjoy a fun 2D game that's easy to pick up and play this game is for you. ... Get this program for free when joining the JGOware Software Membership! ... Why not try the free trial right now?
http://jgofiles.com/download/RoidsSetup.exe - 6Mb - Download - Screenshot

Warp Assault
Warp Assault is a flat-out fun blast-em-up, and it runs on anyone's Windows desktop! No strategy, no hard choices, just level after level of pure adrenaline action. Perfect for the lunch-hour, or whenever you just feel the need to blow up aliens! Inspired by Robotron, Warp Assault pits your lone... Powerups include Xtra Life, Xtra Shield, Mirror, Cloak, SuperShot, and MultiShot, and all these powerups are cumulative, so after four MultiShot powerups, your ship fires FIVE hot beams of devastation!
http://aggressive.swmirror.com/wassault.exe - 2Mb - Download - Screenshot