In 1995, Delphine Software released a 3D sequel to their 2D platformer Flashback. Entitled Fade to Black, it was the first attempt to bring a popular 2D platform game series into 3D. While it retained the puzzle-oriented level design style and step-based control, it did not meet the criteria of a platform game, and was billed as an action adventure.[21] It used true 3D characters and set pieces, but its environments were rendered using a rigid engine similar to the one used by Wolfenstein 3D, in that it could only render square, flat corridors, rather than suspended platforms that could be jumped between.