The complete rules · The forty-three certificates · The mathematics
© 2026 Parker M. D. Emmerson. All rights reserved. Counterfoil, THE WINDOW, the Contra-Zero Certificates, and the texts they are built on are the copyright of the author.
A two-seat strategy card game built on THE WINDOW (Contra-Zero Certificates): forty-three certificates, thirty strokes kept at every transition, three scoring columns compared and never added. The game needs JavaScript and WebGL; the complete rules and every certificate are plain pages.