Marco Rossin joined the MRC Under Water Challenge with an entry called Madfish. In this turboR demo for MSX-DOS2 you can control a 3D-modeled fish with your cursor keys and space bar.
As of today, a follow-up to this demo can be found in our ever growing Downloads section. The new demo, Madfish 2 has been optimized. A 3D cube (aquarium) has been added, which can be controlled with keys 1 to 6 of the numeric pad.
Relevant link: Madfish 2