Yume Koujou: Doki Doki Panic
|Yume Koujou: Doki Doki Panic|
Doki Doki Panic (Heart-Pounding Panic) is a side-scrolling platformer developed by Nintendo in collaboration with Japanese TV network Fuji TV in order to help promote their 1987 Yume Koujou (Dream Factory) event. The game revolves around an Arabian family who must venture into a dream world inside a storybook in order to rescue their two youngest children from the evil ruler Wart.
It is better known in the west as the game that served as the basis for the international version of Super Mario Bros. 2, with many of its original elements and characters ending up being incorporated into the Mario canon through their inclusion in subsequent games.
There could be some unused graphics other than the smiley face.
Inside the tileset for the desert stages is a little smiley face that isn't used anywhere in this game or the prototype and final versions of Super Mario Bros. 2. It appears to just be a placeholder.
Original/authorized copies of Doki Doki Panic have the file count for side B in the disk header intentionally set to 13, rather than 14 (the actual number of files on the disk). Unauthorized disk copying tools originally relied on this value to know how many files to copy to the new disk, and as a result, would end up skipping the very last file, appropriately named DUMMY-DT. The game uses a specific BIOS call to search for this file's ID number ($C0, or 192) when loading data from side B, and if it is not present, the screen shown to the left is displayed.
Interestingly enough, the DUMMY-DT file is actually loaded into RAM at $6600, though it contains nothing more than an empty save file and two signature bytes (00 00 00 00 5A A5). The real save file from side A has already been loaded into RAM and copied to an alternate location by the time this file is loaded, so its actual contents do not matter.
To see this screen, remove DUMMY-DT from Side B or set the PC to $66A2 before entering a level.