The current “sight” is based on chemoreception, with planned eyespots to see patches of light.
When the player grows their organism, the range of chemoreception would reveal less relative to the organism. I’d say that a depth of field blur would be most appropriate for range.
Of course, there are many ways to perceive the world that aren’t just sight. Different types of perception would probably give some kind of baseline light-perception to be able to see the game world, with different strengths and weaknesses. Material shaders could have parameters to reveal senses.
Light - [ +habitable planets have sunlight, +longest range, doesn’t work in the dark ]
active component: bioluminescence
Infrared - [ +detect active creatures, +detect heat spots, heat dissipates easily / short range ]
(subset of light, but interesting enough)
Smell - [ +tracking, +detect chemicals, -dissipates easily, doesn’t work on inorganic things ]
active component: general biology
Sound - [ +detect active creatures, +works out of sightline, doesn’t work on unmoving things ]
active component: echolocation
Vibrations - [ +see through walls, must be on ground ]
(combines sound and touch)
Electric - [i don’t understand this enough to gamify it]
active component: electric eel stuff
Other senses could just provide live readouts for environmental values (as is displayed in the patch map). Senses that have not been developed to widely perceive the game world could also just be readouts - like temperature, self and ambient volume, pressure, whatever. Undeveloped hearing would muffle or damp in-game sounds, as well.
Magnetic senses would give the player an on-screen compass.
Radioactivity is an afterthought, but if life happens to evolve around it, those organisms would find a way to detect it.