I want to build a side-scrolling 2D diving game prototype, with a glowing jellyfish as the protagonist swimming in the deep sea. The visuals should feature realistic underwater lighting: visible water caustics and subtle refraction, with overall illumination primarily driven by the jellyfish’s bioluminescence and a faint diffuse fill from above to simulate under-ice light. The jellyfish’s tentacles should exhibit soft-body behavior—flexible and drifting—with lag, sway, and spring-back in response to speed, turning, and currents. The gameplay only needs basic movement, collision, and camera follow; the water lighting effects can be implemented using GLSL shaders. The goal is a runnable prototype with switchable effects, tunable parameters, and stable operation on common hardware.