Astro Warrior's three levels each have many different kinds of enemies that attack in various patterns. The stages themselves have no obstacles, it is only the enemies you'll be dealing with. There are, for example, your typical little ships that travel in rows, ships that swoop down the sides of the screen, and even things that look like giant spinning cheesewheels. Like most shooters, learning the enemies' patterns and how best to deal with them is the key to success in Astro Warrior. Also as important is collecting power-ups, which can be accomplished by shooting at targets on the ground. You will need these power-ups because the game is unplayable without them, especially the speed-ups. Without speed-ups, your ship moves way too slowly to do much of anything. The other power-ups include a stronger laser weapon and two Gradius-style options.

At the end of each stage is one of three large bosses, whose names are Zanoni, Nebiros, and Belzebul. These bosses are really easy to deal with once you learn their patterns, none of which are too tough to memorize. In fact, most of Astro Warrior's first loop is very easy. It's the second loop where things start to get more difficult.

Upon beating the final boss, Astro Warrior loops back to the beginning. There is no real ending to this game, it just loops forever. At the second loop and beyond, the enemies move faster, there are more of them, and many of them now fire bullets when they hadn't before. One of the toughest parts of Astro Warrior is getting through a gauntlet of blue crystal-like enemies in Levels 2 and 3. They're grouped in pairs of two, and if you shoot one, the other rockets forward really quickly. They are easily avoided on the first loop because they don't shoot bullets, but on the second loop they do. This can cause the screen to become quite cluttered. Even with a lot of speed-ups, dodging is not very easy in this game because your ship is so huge and the control is not very intuitive (it's nowhere near as smooth as the control in Zanac). This is why being fully powered-up with the lasers and options is a must. Most of the challenge I got out of this game was from making a mistake in the final level and then finding my ship unable to deal with the onslaught of enemies and bullets without its power-ups.

The first and last bosses have an extra bullet pattern on the second loop, but that doesn't really make them any more difficult to deal with. (There is no change to the second boss at all.) Ironically, the final boss, Belzebul, is the easiest one in the game, although he must be taken out quickly because he'll ram into you if you take too long. This attack, as it would seem, cannot be avoided. Neither, perhaps, can the fate of the Astro Warrior pilot, as the game taunts you with a peculiarly strange phrase after beating each boss. Upon destroying the first boss Zanoni, the message "Surely revive Zanoni" then flashes on-screen. This happens again for Nebiros and Belzebul. Was this something that got mistranslated, or were the programmers rubbing in the fact that the game never ends?

While I did have some fun playing Astro Warrior, and I eventually completed both loops (the third loop was the same as the second), it's not a game that I'll be coming back to over and over again. Even though the second loop is considerably more difficult than the first, the game is still rather easy. As far as 2D shooters go, I'll take Zanac, Abadox, Life Force, Dragon Spirit, Super Earth Defense Force, or Gradius 3 over it any day of the week. But if you own a Sega Master System, it's a game that's worth picking up for a cheap price. And it has the phrase, "Surely revive Zanoni"! Surely, that's gotta count for something!