Bit Blaster XL is a perfect example of how to make a great little indie-game. First pick a classic genre, in this case space shooters. Pick a gimmick or two to make your game stand out from other similar titles. Finally, give the player a some motivation to continue playing beyond just for high-scores. One easy way to achieve this is via a light progression system. Bring all that together like this game does and you're destined for success.
The developer's motto "live, die, retry" becomes quite apparent very quickly. Bit Blaster is a space shooter similar the classic Asteroids. There are various meteors, bombs, and spaceships coming at you from both sides of the screen. The longer you survive the more stuff gets thrown at you. Its usually not much more than two or three minutes till you're overwhelmed and you're ship is destroyed. You'll want to keep jumping right back into the action because with the aid of the various weapons you'll know there is potential to do better.
The weapon and ammo system is one of the features that really stands out about this game. You have one ammo base that carries across for all the different weapons including your standard gun. In order to get more ammo you'll either have to pick it up from destroying the objects around you or grabing new weapons. Once you pick up a weapon you're stuck with it unless your ship gets hit, runs out of ammo, or you pick up a different weapon. There are classic weapons like rapid fire, scattershot, and homing missiles as well as unique ammo that either explodes, bounces, or tears through multiple enemies.
To help keep you motivated you earn coins as you play which will unlock you new ships. The first couple ships offer a specific selling points such as extra speed or multiple shields. As you unlock the later ships they are pretty much straight up upgrades of previous models. By the end of the game there will probably just one or two clear favorites you usually stick with if you choose to keep playing. There is some incentive to go back to the other ships as each has their own leader-boards for high-scores.
Either you like retro space shooters or you don't. If you do Bit Blaster is definitely worth checking out. The various weapons and ships make it quite an enjoyable game that can be hard to put down. Since it is rather light you may not be very motivated to keep playing after unlocking all the ships but you'll still have had enough fun up to that point to have made the purchase worth wild. There are bits that need blasting, how much more need I say.