A friend of mine recently introduced me to this neat little freeware game here:
http://www18.big.or.jp/~hikoza/Prod/index_e.html
Basically, It's a scrolling shooting game. Thing is, though: All the enemies are bosses. The first battle with a small, simple ship called the Pure Heart is over quickly. The next boss however, builds on the areas you exploited. Repeat this process a few times and you have a hulking colossus that fills half of the screen, firing tracking missiles and Vulcan cannons at you from every angle.
Fortunately for you however, lives are plentiful. You don't even have to worry much about lives, in fact. You just lose 20 seconds each time you die from a timer in the corner of the screen that steadily counts down on you. Nothing at all in the way of power ups, but you're equipped with a 360 rotating cannon that can take care of just about anything with enough elbow grease. You can also gain some time back at the end of each round if you do well enough.
Enjoy!
WARNING: THIS GAME IS HIGHLY ADDICTIVE. PLEASE USE EXERCISE CAUTION WHEN PLAYING FOR EXTENDED PERIODS OF TIME, OR UNDER THE INFLUENCE OF TECHNO MUSIC.