Alien Blast is basically
Beachhead 2002 with a dash of aliens and a twist of sci-fi. For those of you who don't know anything about
Beachhead 2002 (don't worry, you're not missing anything), its entire premise is comprised of gunning down enemies from a stationary turret. That's what
Alien Blast is like, except this time you're blowing up aliens instead of paratroopers.
Of the 8 weapons you can use, only a few are really worth anything. The machine gun you have initially has unlimited ammo, and the rest have to be obtained and armed with power-ups. These power-ups are dropped from an allied ship floating around in the sky, and all you have to do is shoot them to reap the benefits from within.
Of the 45 levels in the game, you'll be lucky to get through more than three. Each level is the same thing over and over again; kill all the aliens thrown at you, whether from the ground or air, and don't die. Every few levels, a new type of alien will be added to attack you, but after a couple of missions the differences between the new aliens and the ones you've been staring at are hard to distinguish. Luckily, you can easily jump to any level by hitting F9 and then typing 'load level xx', and hey presto you're there.