tap and a pulse expands from the tap at a fixed speed of propagation. when the wavefront meets a wall the wall is briefly lit at a brightness that falls with the round-trip distance. between pulses the room is not quite dark and not quite lit. space emits from the cursor; r re-scatters; s toggles chirp; h toggles hunt.
in hunt mode a moth wanders the room. it is never drawn directly — it is only visible where a wavefront happens to sweep past it, marked warm against the cool wall echoes. tap where you last saw it. a tap within catching distance of its true position ends the moth's evening; a tap elsewhere is logged as a miss and the moth keeps flying.