Basically, for any moon you choose, there are two stages you must complete. First you fly though space avoiding or shooting asteroids and other objects which can destroy you, collect power-ups and weapons, until you reach the boss at the end. The first stage is similar on all the moons. There are asteroids of some type, crystals, blobs, glass cubes which can fire at you, and spheres which also fire at you.
If you defeat the first boss, you will continue on to battle baddies over the moon's surface until you reach the second boss at the end. You will have freed the moon after defeating the second boss, and then you will return to the galactic map to choose your next mission. Some levels have additional obstacles, such as on one moon you fly in a cave and cannot fly to high or to low without hitting the stalactites and stalagmites, and must avoid falling ones.
Compared to the hyperactive Defender 2000, Trevor McFur's gameplay is slower. That doesn't mean the game is easy though. The enemies range from teeny-tiny to huge in size. Like D2K, your ship is kinda big, which makes maneuvering around objects difficult (especially the bosses!). This is a pain whenever you're flying in space trying to avoid debris, especially when you move up or down.
Some of the background graphics look impressive. Others look like cheap PC screen backgrounds. The enemies look like flat pictures moving around the screen firing at you, not 3D at all. Also, the space debris in the first stage of each moon look like they were taken out of the game Maelstrom for the Apple Macintosh.
Although there is no music during gameplay, there's background music during the title screen and the galactic map screen. However, the music is pathetic. It sounds like bad tunes from the Star Wars Cantina group. It's a good thing there's no music during gameplay if it was going to be anything like the music from the title screen.
The sound effects in this game are nothing spectacular either. There's the explosion sounds, which are alright. When you shoot a blob it makes the sound of a bubble popping. Then there are the sounds of the enemy's fire, which varies from sounds like small firecrackers to squishy sounds.
Keep in mind that this was one of the first games released for the Atari Jaguar, so it may have been something back when the Jag was first released but falls short by today's standards.