Sentient Sketchbook is a tool which supports the design of map sketches via an intuitive interface, via real-time feedback regarding the map's playability or balance, and via the suggestion of alternative map designs. The tool assists the level designer as it automatically tests maps for playability constraints, calculates and displays navigable paths, evaluates the map on gameplay properties and adds details to the coarse map sketch. Additionally, the tool aims to inspire the designer through the suggestion of map alternatives generated via genetic search.