A brilliant game. It's a shame the GBA and GBC versions got cancelled. I would have played them 100,000,000 times over.
It's your standard shoot em up, but done well on so many levels it's unheard of. There are two completely different ways to play the game. Full Game is a more difficult mode, where you have one life. If you lose the life, you have to reset the level. You can spend the points you earn during levels on better ships, shields, generators, weapons and sidekick weapons.
You can also play on Arcade Mode. On Arcade Mode you have no upgrades, but you can collect purple balls to give yourself more lives. The more lives you have, the stronger your weapons become. You pick up weapons during the game in this mode, and you can go 2-player co-op.
If I knew how, I would donate the creators of this game £100. I would pay that much to play this phenomenal game. GET THIS GAME NOW. It's free to download (and perfectly legal) at http://www.freewebs.com/worldtreegames so go get it, start up a DOS emulator, and enjoy one of the greatest games to ever bless our keyboards. Amen.