The Gecko is a small lizard that has appeared in one Rusty Lake game.
Samsara Room[]
In the Normal Room, there is a gecko on the wall that crawls away when William tries to pick it up. After eventually catching the gecko in a jar, it can be used on window portal. This leads to the Gecko Room, and turns William into a gecko himself. Walking on the ceiling, he now can reach the bookshelf and knock the Samsara Book down to the ground. Later in the Normal Room when William plants a seed in the flower pot, it grows into a flower so tall that it can only be reached as the gecko.
Once William reaches the Bird Room, he sees a stork in a bird's nest. By feeding the stork the gecko along with the heart, the worm, and the fish, it will vomit out a baby, which is in fact his own reincarnation.