rE/Generation is a freeware remake of D/Generation. The original levels are recreated with enhanced graphics and sounds, while the storyline is expanded to accommodate new scenarios and effectively create a sequel as well. The main objective remains the same: to infiltrate the headquarters of a bioengineering company called Genoq, whose unnatural creations got out of control and started to roam free in the many rooms of the installation, threatening the people trapped in the building.
The game is rendered in isometric graphics, with the player controlling the main character and guiding him towards switches and other clearly marked interactive places of the scenery, to open passages to adjacent rooms. Some areas contain other humans who must be rescued and guided to the nearest exit. Some of them have information that advances the plot, and the player receives an extra life for every person saved. There's no action button per se, only the cursor keys or numeric pad for movement, and three buttons for the laser gun, grenade and shield, with all the other actions being performed by bumping into switches and other scenery. Blue doors open via yellow wall switches, while green doors are locked and require a keycard and red doors only open after all the monsters are eliminated and all the vents are closed. Yellow switches can be activated by lasers shots, grenade explosions or roaming enemies. The game progress can be saved with the "S" key, and loaded later from the main menu.