Namco's 1987 fixed shooter arcade game Galaga '88 (which is the fourth title in their Galaxian series) is divided into twenty-nine stages over five dimensions, each one tougher than the last. The first three stages of the game will always take place in the first dimension and do not feature any obstacles at all, which means that the only way to collect a blue Warp Capsule in either of the first two stages is to wait for two Goei to meld with each other and create an enormous version of themselves; once you have hit the aforementioned enormous Goei three times to kill it (it will change color each time you do so, much like the Octy did in Namco's own Baraduke), it will leave a blue Warp Capsule behind. The next four stages of the game will take place either in the first or second dimension (depending on whether you collected two blue Warp Capsules over the course of the first two stages) and feature Crystal as obstacles until the formations of enemies have fully assembled - they take one hit to destroy, and will leave a blue Warp Capsule behind once you have done so. The next three stages of the game will take place either in the first, second or third dimension (again, is depending on whether you collected two blue Warp Capsules over the course of the first six stages) and will always be scrolling forward until the surface of the planet vibrates and a formation of enemies instantly appears in front of you; they also feature Asteroid and Amoeba as obstacles, which take eight and sixteen hits to destroy respectively but will not leave a blue Warp Capsule behind once you have done so. The next four stages of the game will take place either in the second or third dimension (yet again, depending on whether you collected two blue Warp Capsules over the course of the first seven stages and the fact that you will automatically warp into the second dimension without a bonus if you are still in the first dimension after clearing the tenth stage), and feature Asteroid as obstacles for a second time - once again, they take eight hits to destroy but will leave blue Warp Capsule behind once you have done so this time. The next four stages of the game will take place either in the second, third or fourth dimension (for a fourth time, is depending on whether you collected two blue Warp Capsules over the course of the first thirteen stages) and feature Cosmo-Mine (from Namco's own Bosconian) as obstacles; as with the Crystals, they take one hit to destroy, and will leave blue Warp Capsule behind once you have done so. The next four stages of the game will take place either the second, third, fourth or fifth dimension (for a fifth time, this is depending on whether you collected two blue Warp Capsules over the course of the first seventeen stages) and feature Asteroid as obstacles for a third time - yet again, they take eight hits to destroy and will leave a blue Warp Capsule behind once you have done so, even if you are in the fifth dimension. The next four stages of the game will, once again, take place either in the second, third, fourth or fifth dimension (for the sixth time, this is depending on whether or not you collected two blue Warp Capsules over the course of the first twenty-one stages) and feature Ameoba as obstacles for a second time - once again, these take sixteen hits to destroy, and will leave a blue Warp Capsule behind once you have done so, even if you are in the fifth dimension (again). The final three stages of the game will, yet again, take place either in the second, third, fourth or fifth dimension (for a seventh and final time, it is depending on whether you collected two blue Warp Capsules over the course of the first twenty-six stages) and will always be scrolling forward until the ground of the spacestation vibrates and a formation of enemies instantly appears in front of you for a second time; they also feature Asteroid and Amoeba as obstacles for a fourth and third time, which, yet again, take eight and sixteen hits to destroy respectively but will, once again, not leave a blue Warp Capsule behind once you have done so. The ending message you will receive after clearing twenty-ninth stage depends on which dimension you were in for the final three stages of the game - second, third, fourth or fifth.
The Boss Galagans will attempt to capture your ship by flying down and engaging their tractor beams much like they did in the original Galaga, and this time around they have this power to capture it if it is a double ship; as in the original Galaga, a captured single ship will turn red, but a captured double ship will turn blue as the text "FIGHTER CAPTURED" appears on the screen. An updated version of the original "Fighter Captured" theme will then be heard from the Yamaha YM-2151 as the Boss Galagan takes your captured single or double ship back to the top of the screen while your next single ship materializes at the bottom of the screen - you will then have to fire two shots at the Boss Galagan that captured your single or double ship while it is attacking to kill it. Once you have done so, your captured single or double ship will return to its original silver color and spin around in mid-air for a few seconds before rejoining your current single or double ship at the bottom of the screen in order to become a double or triple ship (the latter of which was created especially for this game); however, that triple ship cannot in turn be captured by the Boss Galagans and retrieved in order to create some kind of "quadruple ship", and the game will be over if you get captured without any lives remaining.
The third, seventh, fourteenth, eighteenth, twenty-second and twenty-sixth stages of the game are Challenging Stages; once your ship has rematerialized at the bottom of the screen, the text "THAT'S GALACTIC DANCIN'" will appear on the screen as an updated version of the original "Challenging Stage" introduction is heard from the Yamaha YM-2151. There are sixteen different types of Galagans that are exclusive to these six stages, and three of them are smaller versions of the escort enemies that are exclusive to the twenty-three regular stages - but, unlike their enormous counterparts, they will not fire a hail of bullets down at you (much like the other thirteen bonus enemy types). If you manage to fire a shot at all forty of the Galagans on one Challenging Stage to kill them, the text "PERFECT! NUMBER OF HITS: 40. SPECIAL BONUS! 10000 PTS" will appear on the screen as an updated version of the original "Perfect Challenging Stage" theme is heard from the Yamaha YM-2151; however, if you missed even one of the Galagans, the text "NUMBER OF HITS: XX. BONUS XX00 PTS" will appear on the screen ("XX" being the number of Galagans you have killed). But if you refrained from touching the controls at all, you will receive a "Secret Bonus" which can range from 10000 to 25000 points and it depends on the dimension that you are currently in - and if you managed to collect two blue Warp Capsules, they will rise up from their positions at the bottom of the screen and explode, creating a dimensional rift in the process. Your ship will then pass through the rift to the next dimension; however, if you only managed to collect one blue Warp Capsule, it will rise up from its position at the bottom of the screen and dissipate while your ship dematerializes and proceeds to the next stage in the same dimension. But if you didn't manage to collect any blue Warp Capsules, your ship will simply dematerialize and proceed to the next stage in the same dimension in the manner of it had only collected one blue Warp Capsule.