Initial Concept:

Using breathing to control buoyancy - using breathing to control the distance with coral reef

Coral reef turns white / decay when fins touch - sustainability

Using bubbles - fish swim away when breathing

Using sound to recreate the breathing sound

Fish attack - game logic

Ocean wave like lighting

Reference:

https://www.neilmendoza.com/portfolio/disruptive-devices/

Look:

old camera box - head poking in

Logic:

ICM - breathing sound?

Idea 1 &2: