Asteroid ES
Arcade Style Space Shooter
http://members.gamedev.net/battleline/asteroid_es_0_80_01.exe - 4Mb - Download - Screenshot

Asteroid F
Asteroids collide and aliens attack out of no where firing indiscriminately in this free arcade style space shooter game for the PC.
http://www.freewareshareware.net/download/af.exe - 1Mb - Download - Screenshot

Clash N Slash
Enjoy non-stop action space shooter with extremely simple controls suitable for all ages! Clash'N Slash, a totally new and highly addictive arcade space shooter for players who want to enjoy a fresh exciting gameplay and bored with playing tons of indistinguishable shooter games. ... In Clash'N Slash arcade game you must defend your planet from pesky alien invaders that will arrive from all around the galaxy. ... Loads of weapons, upgrades, enemies will hold you for a long time and innovative bonus triggering system will make your game experience colorful and fun.
http://www.enkord.com/download/clash_n_slash_111.exe - 5Mb - Download - Screenshot

Arcade Force Game Directory Browser
Arcade Force is an Internet directory for online (web browser based), console, PC, and emulation games, cheats, and resources in a comprehensive range of game categories and platforms. Game categories covered include action, adventure, fighting, horror, Internet, pets, platform, puzzle, racing,...
http://64.34.164.24/setup_af.exe - 1Mb - Download - Screenshot

phoenicas
After a successful alien attack on earth, only 6 humans escaped. Five are onboard non-firing space vessels and one (you) is piloting the only remaining fighting craft. Your mission is to guard the vessels on the journey to safety. Aliens will attack the convoy and try to kill you and abduct the... Phoenicas is an arcade musical 2d shooter in the styles of defender, exerion, phoenix, ikaruga and space invaders. ... Use of a proper arcade joystick like hotrod or x-arcade is highly recommended. ... Phoenicas is an old school score-driven 2d shooter.
http://www.phoenicas.com/phoenicas/phoenicas_demo.exe - 16Mb - Download - Screenshot

Gunstorm
Gunstorm is a single screen space shooter. Mouse or keyboard controlled, Gunstorm is a top down arcade game where the player must ascend through ever-changing levels of alien waves, meeting different guardians along the way. Several game types are available, including a superb Asteroids inspired... Fully 3D and using the Cornutopia Hector graphics engine, Gunstorm represents the most advanced game in a series of releated shooter titles stretching back to 1992. ... Different weapons and enemy combinations, and different level types and guardians have all been extensively adjusted to make...
http://www.cornutopia.co.uk/software/taskforcesetup.exe - 3Mb - Download - Screenshot

The Best Arcade Game Ever
Blow away fighters coming at you from all directions as you explore HUGE worlds, and collect alien artifacts in this omni-directional 2D shooter hosting some briliant 3D graphics. Collect various types of weapons and energy left behind by your enemies as you blast them out of existance. ... The game mixes elements of classic arcade games with elements of modern 3D games. ... The game also hosts an energetic music track, but if you prefer your own music, just pop you favorite music CD into your CDROM drive, and the game's music engine will integrate the music from the CD into the game.
http://www.best3dgames.net/bestarcade/bestever.exe - 14Mb - Download - Screenshot

Cosmic Defender
Based on a classic arcade retro game, this side scrolling shooter is pure addictive endless fun. Destroy the invading aliens and save your brethren from abduction. Compete against other players via the Internet high score board. Free game with no spyware brought to you by 2DPlay.
http://www.2dplay.com/cosmic-defender/CosmicDefenderSetup.exe - 891Kb - Download - Screenshot

Alien Invaders Attack!
Free arcade style space shooter game for the PC.
http://www.sci-fi-game.com/download/aia.exe - 4Mb - Download - Screenshot

Space Alien Invaders
Free arcade style space shooter game for the PC.
http://www.freewareshareware.net/download/sai.exe - 1Mb - Download - Screenshot