During the late '90s Squaresoft published a variety of titles outside of the RPG genre for which they were known, including racing and shooting games. Internal Section was one of those unique titles that the company never published outside of Japan after its initial release on January 28th 1999.
Similar to Tempest, the player takes control of a nondescript polygonal "ship" that slides around the inner wall of a tube. However, unlike Tempest the player's screen position remains locked at the bottom center of the screen so as to be less disorienting. As enemies and obstacles approach, the player can move left and right to line up shots or avoid them, respectively. Thanks to its experimental and non-linear design, Internal Section allows the player to play the levels in sequence or practice any level immediately from the start screen.
Levels are broken up into 4 phases, during which the player can score points by eliminating every enemy in each wave. Some waves consist of indestructible panels which the player must simply dodge, and one mini-boss will attack. After the player has reached the terminal, a boss battle ensues followed by a short bonus round wherein the player can collect multi-colored balls.
Interestingly, the game allows the player to cycle between 12 different shot types based on the Chinese zodiac without requiring any sort of power-ups or "drops". Each one is named after its associated zodiac (horse, snake, dragon, monkey, etc.) and has its own unique style and pattern. For example, "rat" is a simple straight-forward rapid fire shot while "bird" looks more like boomerangs which shoot out to the left and right and crisscross further ahead. The "snake" shot is a long unbroken laser that glides and weaves around the tube until it connects with something. The "dragon" shot is a short fan of fire that can absorb enemy bullets. Since the player doesn't have to wait to use all of the zodiacs, the game seems to encourage experimentation, and as you cycle through them your ship morphs into varying shapes. With experience, the player comes to recognize which zodiac is best for taking out specific types of enemies.
The player can also use a limited number of "eraseR"s, smart bomb attacks that clear the tube of any enemies and incoming fire.
Each level ends with a boss, with the perspective changing from a tube to a flat horizontal ring which encircles the boss. The player's ship remains pointed directly at the boss, but can move around it in 360 degrees to avoid incoming fire or to attempt to line up with the boss's weak point. The bosses can be quite challenging as you are unable to disconnect from the circle and can be easily trapped by enemy fire.
Internal Section runs at 60 fps and features sharp, bright, and colorful abstract shapes. A combination of both wire-frame and textureless flat-shaded polygons are used, which pulsate and change color with the music creating the effect of a psychedelic kaleidoscope similar to Rez
. Some of the bosses are textured, for example one of them is (oddly enough) a newspaper.
The music is fairly standard but fitting techno/electronica stuff, and like Ridge Racer
the game cd can be swapped for any music cd of your choosing after it has loaded. The graphics will react differently to the music based on its tempo.