The second row of the main page states this: "The first concern of toy is to bring the thinnest and simplest stack of technology for making games directly from

The second row of the main page states this: "The first concern of toy is to bring the thinnest and simplest stack of technology for making games directly from C++, instead of focusing on a monolithic editor, or insulating the user from the core systems." So I think this is "thin and wide", instead of "thin and small". Having all the components you need and having them directly accessible counts as thin in my opinion.