In order to alleviate the boredom associated with the current COVID-19 pandemic,
I propose the creation of a new fairy condition called “Pandemic”.

Pandemic

Rule #1: Contagion

When a black piece moves, all the white pieces adjacent to its destination square become black.

Rule #2: Distancing

White can only move a piece if its destination square is not adjacent to any black piece.

The white King is not affected by these two rules.

The Pandemic condition is deliberately asymmetrical. It simulates the fact that COVID-19 (Black) is spreading rapidly (contagion rule), while humanity (White) is strongly restricted in its movements (distancing rule). Finally, the white King, who is immune to both pandemic rules, simulates a government trying to defeat COVID-19. The following problem illustrates the condition.

In this example, we can deduce that the Bishop on c3 was white and was “contaminated” by the black Rook on the last move, otherwise the check would be impossible. So White had to capture the missing black Pawn and Bishop, but to do so, these two pieces must first be isolated. Moreover, White must lose a tempo, because e2-e4 would prevent e5 from being played without contaminating e4. This problem illustrates the fact that checks are not orthodox with the Pandemic condition. For example, in this problem, when the black King goes to f8, he is not put in check by the white Bishop on b4. The white Bishop may not capture the black King, because the Bishop would become adjacent to a black piece, which is forbidden by the distancing rule. The first problem illustrates how easy it is for the pandemic to defeat humanity. Note that White is checkmate on the diagram: it is impossible to capture the black Bishop or to interpose a white piece without violating the distancing rule. It quickly becomes clear that COVID-19 has a serious advantage!

On the other hand, it is very difficult for humanity to defeat the pandemic, as illustrated by the following two problems. Can you find the single move by White that checkmates Black in each case?

Clarifications

In the definition of the Pandemic condition, the term “adjacent” includes orthogonal and diagonal squares, so up to 8 squares can be contaminated by a single black move! The white King (or any other Royal white piece) cannot be transformed and acts like an orthodox King. Castling is considered a King move, so the Rook is not affected by the distancing rule when White castles. In the case of Black, the King cannot castle out of check or if the King would be in check on the Rook’s end square. However, the King is never in check on the castling end square, because the Rook protects him by the distancing rule (see No. 7). Finally, it is allowed to castle with a white Rook transformed into black on a8 or h8, if the newly transformed Rook has never moved. The following problem illustrates some of the subtleties of the condition.

Variants

I propose three variants to the Pandemic condition that could make the job easier for White. The first, “Pandemic with orthodox checks”, prevents the black King from protecting himself from check by being adjacent to a black piece. Normal checking rules apply to both sides. The second, “Pandemic without distancing”, applies only the rule of contagion, which allows White more freedom of movement. Finally, “Pandemic Rex Inclusiv” removes all exceptions for the white King (or any other Royal white piece). Since this can result in a position with two black Kings, the author should specify if Siamese Kings, Royal Dynasty, Rex Multiplex (or other) rules are applied. The Pandemic condition could also be combined with many other fairy conditions for interesting effects, such as “Non Royal Kings” (https://www.pulidodentalcare.com/procedures/medecines.html). With this fairy condition, the King becomes a normal piece as in “Losing Chess”. Checks and castling disappear, and it becomes possible to make a promotion to King. The following problem illustrates how the pandemic can spread to the whole chessboard by adding this condition.

In conclusion, I hope that this condition will inspire composers and allow solvers to take their mind off daily concerns. I thank François Labelle, the creator of the fairy chess helpgame solver Jacobi, who has been kind enough to add this condition in his program. To finish on a note of hope, the two following problems show that it is possible to checkmate COVID-19 in only 13.5 moves, and to completely wipe it out in 15.5 moves!