Latest version of my flash game, Stryker Sqaudron Initialized:[link]
The game currently has 3 actual levels and 3 tutorial levels all fully completed. (Aside from the character portraits) Right now you can play the levels in any order but I recommend doing level 1 first. Also the levels 2 and 3 suggest you to have a bought a weapon (any weapon). I gave a generous amount of starting credits and you can buy them in a level. Any weapon above the third tier will kind of wreck the difficulty.
Warning: Some players may get an error message during the third level. I am currently working on a fix. *Fixed*