Glass (1993, Arcade)

Glass is a shoot'em up developed and published by Spanish company Gaelco. It was only released in the arcades.

You control a pilot to destroy the worlds of an alien species after they have attacked Earth.

The game has a softcore erotic aspect, as you uncover images of topless women by beating stages. The game is divided into wrolds. Each world consists of four stages. After each stages, more parts of an image are revealed, and you get to see the full picture after the forth stage.

Each stage consists of a single screen. At the beginning, the whole screen is covered with tiles. Flying your spaceship over tiles will remove them. Once you have remove all tiles, the stge is completed. Enemies will enter the screen from various entries, and the game also indicates from entry an enemy will enter next. You have a shot and a limited number of bombs to kill off enemies. You die on one hit, but you have limited number of energy shields which make you invincible for a few seconds. Sometimes enemies will drop extra shields, extra bombs or stronger weapons.
The forth stage alway consists of a boss fight. If you loose your life during a boss fight, the boss's health will be fully recovered.