The SYD mission was successful, but the current era was only one place under attack. The invaders also traveled back in time, hoping to rewrite history. Only the six experimental space-time battleships known as ZIG could stop them, but they were attacked upon taking off. Now trapped in the past, they have no way to return to the present.
Bermuda Triangle is a scrolling shooter designed by the same team as Ikari Warriors. The player must survive each of the 9 levels, which automatically scroll both up and down, long enough to reach and destroy the boss. The ZIG, being a much larger ship than most scrolling shooter ships, can sustain several hits before being destroyed, and has both a straight ahead shot and a rotating turret that can fire in 8 directions. SYD ships can be picked up in levels and will fly near the ZIG in four different formations. They can block enemy shots but will be destroyed if hit by enemy ships. Energy can be picked up as well, which will either restore lost health or, at full health, power up the attack of the ZIG and SYDs.
The arcade version uses a rotary joystick to control the turret, but the PlayStation port places the turret controls on the shoulder buttons.