## Draw, play, erase, correct, scan & play anew! In this talk, we will share our experience in designing games that revolvearound interactive drawings (felt pen on paper, graff on walls, colored syrupon waffles...). How does such games work? First a camera captures the drawing,then we analyze it, use that information in our game, then we project back therendered game on the drawing to close the loop. First we will discuss the implications of such an analogical and free-forminput in term of user experience and possible gameplays. Then we will presentthe tech we have been developing to ease the development process. This impliedworking both on software (a library, the PTX system) and hardware (a kit foreasy setup).