Otocky (オトッキー) is a video game released in 1987 for the Family Computer Disk System in Japan.

[1] Developed by SEDIC and published by ASCII Corporation, the game was conceived and designed by Toshio Iwai.

Completing a certain number of levels unlocks a music editor which makes it possible for the player to freely compose their own melodies.

Otocky is a precursor of Rez, Tetsuya Mizuguchi's 2002 Dreamcast and PlayStation 2 game exploring similar themes of player action and musical evolution.

[2] Jake Kazdal, the only North-American member of United Game Artists, has confirmed that while the team did become acquainted with the Disk System game during the process of creating Rez, it has not been much of an influence in fact.