Inspired by the novel Watership Down, Bunnies & Burrows is a tabletop roleplaying game about intelligent rabbits struggling to survive. It was originally published by Fantasy Games Unlimited, but was later adapted to GURPS Third Edition by Steve Jackson Games.
The GURPS version was created for use with the Third Edition rules, but can be converted to Fourth Edition without much trouble. You will need the GURPS Update conversion guide and GURPS Psionic Powers. Players can get help on the Steve Jackson Games GURPS Forum if needed.
Official Site (GURPS Version)
RPG.net Game Index
Wikipedia Page (GURPS Version)
Wikipedia Page (FGU Version)