First up, Star Defender 4 is an arcade-style shoot 'em up somewhat in the vein of classics like Galaga. As such, you already know what the basic gameplay is like, and there isn't much else about it to shake up the formula. Still, it's worth playing as a straight-up action title for some mindless fun.

You control a ship that moves back and forth at the bottom of the screen using only the mouse. The left mouse button fires the main weapon, the right mouse button fires the secondary weapon. The main weapon is the standard bullet, and it's upgradeable by retrieving the power-up icon dropped by various enemies as you destroy them. Each hit you take, however, decrements the power-up count by one, until the ultimate hit that destroys you.

The secondary weapon comes in many forms: straight missiles, homing missiles, barrier, lasers, saw, flamethrower (in the vacuum of space? really?), parasitron (this weapon fires off a small bug that occupies a fixed position on the playing field for a short duration of time, before exploding and damaging everything within its radius of effect), homing laser, infector, ball lightning, cutter, and machine gun. Each secondary weapon has a limited number of shots, or a limited lifespan; once it's depleted, it's gone for good. You can, however, stack weapons by continuing to catch them as they fall, lengthening their effective duration of use.

These secondary weapons also drop from destroyed enemies, but you can only have one equipped at a time; equipping another will replace the previous weapon, so it's important to beware falling weapons that you don't want.

The enemies themselves come in different shapes and sizes. The basic troops resemble flies and arrive on the scene the most Galaga-like: they drop from off-screen in curling flight patterns, but do little to provide much of a threat. Other, deadlier enemies move faster, fire projectiles that behave differently, and feature specific abilities, like the larger mini-bosses that send up a fireworks-like bullet that floats to the top of the screen, then detonates, dispersing a spread pattern of shrapnel.

The demo lets you play up to the first boss, which is a large mechanical insectoid with multiple strike points. Strangely, the game feels the need to highlight each target on the boss, which ultimately means every part of it. Obviously, you're going to fire at it regardless, so a little less hand-holding would have been fine. Being the first boss, however, it's presumed that this condition won't repeat for subsequent bosses.

You can pick up Star Defender 4 right here on Big Download, for both Mac and PC.