- Luft Chess: standard chess with invisible kings.
- Reverse Schrödinger’s Chess: a variant of Schrödinger's Chess by Darren Provine.
These two variants of chess were created for the exercise “Fog of Strategy” in Chapter 8 of Challenges for Game Designers by Brenda Brathwaite & Ian Schreiber. The challenge given was:
For this challenge, choose an entirely skill-based, non-digital game with no elements of chance at all, such as Connect Four, Chess, or Go. To adapt the game for less competitive players, you’re going to add some chance. Specifically, add “fog of war”: your opponent’s pieces are hidden from you (and vice versa) except under certain conditions.