A tick is the smallest unit of time in games in the Creatures series. In Creatures 1 (source) and Creatures 2 (source), a tick was roughly equivalent to 1/10 a second. In the Creatures Evolution Engine - that is, Creatures 3 and Docking Station - this is equal (in ideal circumstances) to 1/20 of a second at normal speed. If the player runs a single world for around "6 years of solid playing", the game tick is reset by the engine.
See also ket.
Are you looking for the TICK C3 CAOS command?
TICK values in C3/DS
|Time in seconds||Time in hours, minutes, seconds, milliseconds||TICK value in C3/DS|