Pikachu Volleyball (対戦ぴかちゅ～ ﾋﾞｰﾁﾊﾞﾚｰ編) is an old Windows game which was developed by "(C) SACHI SOFT / SAWAYAKAN Programmers" and "(C) Satoshi Takenouchi" in 1997.
This is an OpenAI gym environment of the game created by translating a reversed-engineered JavaScript version by gorisanson to python.