an "old-fashioned feel", reminiscent of the games he played as a child, like Metroid. More importantly, this "retro" design choice allowed him to create a large amount of art on his own, which would have been impossible for a 3D game. At a Game Developers Conference project post-mortem, he emphasized the role of pragmatic design in shaping the game. While designing the main character, "Quote", Amaya drew inspiration from the Nintendo Plumber called Mario's iconic original appearance—a large, expressive face and a high contrast between his white skin and red shirt make him stand out from the dark cave backgrounds. Most other characters feature either light skin or white clothes for the same reason. To make levels memorable, Amaya designed them around a single theme, such as "warmth" for the Egg Corridor, and "arid and oppressive" for the Sand Zone. Instead of a tutorial level, a concept Amaya dislikes, the first level of the game gives the player two paths, one of which is blocked off until retrieving an item from the other path. This setup, inspired by the opening of Metroid, "lets players feel like they've solved problems on their own" and persists throughout the game. In beta versions of the game, all the enemies were shaped like bars of soap, a concept that evolved into the "Balrog" character. There was also a "frog prince" character who could travel through water more easily. Elements of this beta were incorporated into the Nintendo 3DS version of the game. Versions and ports Ports Cave Story has been ported to Linux based, Haiku OS, AROS, MorphOS, AmigaOS 4 and Mac OS X operating systems, PlayStation Portable, Xbox, Dreamcast, Sega Genesis, GP2X, GP2X Wiz, and the TI graphing calculator. An enhanced port, featuring updated character designs, remixed music and extra game modes, was developed by Nicalis and released on WiiWare on 22 March 2010 in North America and 10 December 2010 in Europe. Nicalis also ported the game to DSiWare on 29 November 2010 in North America and 22 November 2011 in Japan. Although it does not feature the enhanced graphics and sound or some of the extra modes from the Wii version, it does include the Sanctuary Attack mode. There is also a free/libre SDL-based recreation of the original game engine, titled NXEngine, made by programmer Caitlin Shaw, which allows for extended modification of the game, and the creation of ports for