Castle Builder slot is an interactive online slot game that was developed by Rabcat. It tells the story of medieval kingdoms where kings marry their daughters off to suitors and house them in newly constructed castles that have been constructed by an old architect. The aim of the interactive bonus game is to construct castles on the left half of the screen by spinning the right symbols on the reels

The online slot game is powered by Rabcat and has five reels with three rows and twenty pay lines. Bets of as little as 0.01 up to the maximum of 2.00 may be placed on every pay line. The game offers a max bet option and an auto play feature.