# How much of a handicap is it to have more than one piece that can't be taken?

In the first Harry Potter movie, Harry Potter And The Philosophers Stone, towards the end, Harry, Ron and Hermione have to win a game of chess while they themselves have to act as pieces. Now, I'm no chess master, but I know that some strategies involve actively sacrificing important pieces on the board in order to secure an overall better board position, or even secure a mate.

In the movie game however, 3 of the pieces are living people, making effectively 4 pieces "of kingly importance" versus only 1 on the opposing team.

My question is, how much of a handicap would it be to have 2, 3 or 4 pieces that are "of kingly importance" while still retaining their original move pattern, and which positions should I put myself and my two friends in (excluding the king) to minimize the risk of harm, while still having a meaningful set of pieces I can either attack with or sacrifice?

• My guess would be that you should use knights for the living people pieces. And I feel it would be a bigger handicap that not having the pieces at all, so quite significant. Nov 17, 2022 at 14:41
• I feel like the answer to question 1 will depend a lot on whether your opponent knows which of your pieces are people, and (separately) whether capturing a human piece means that your opponent wins or merely that you lose a friend and play on (in which case the game would no longer be zero-sum). Nov 17, 2022 at 21:42

The side not having the 3 extra "king-like" pieces does definitely have a decisive advantage from the start. Pick queen and rooks as the additional pieces that you can't lose and there's pretty much no hope. Pick pawns and it'll be extremely easy for the opponent to sacrifice a queen for one of them. Best chance for the handicapped player would probably be picking the rooks and a knight and hope their opponent falls for something like Scholar's Mate

A perhaps fairer game would be one where the opponent doesn't know which pieces are "king-like."

Such pieces are known in the problem world as “royal”. The general condition of having multiple kings is known as “Rex multiplex”.

The first question is what constitutes mate in such a situation. There are really three main approaches I’ve encountered:

(1) All royal units must be simultaneously and individually mated. (2) All must be checked simultaneously, and as long as no move releases all checks, the position is mate. (3) “Dynasty” Such pieces behave as if they are not royal, until only one is left.

Only in (2) is it disadvantageous to have multiple royal units. So let’s assume we are playing with this rule. The general principle is to avoid exposing the king until the endgame, and the same principle would apply.

If one must attack with a royal piece, it should be the queen, as it will have the maximum chance for evasion. But an opposing non-royal queen is very powerful against it because there is no chance of exchange.

Maybe royals should be clumped together, since there is then only one area to defend, and the royal units can help protect each other.

Some problem conditions aren’t very interesting when applied to over the board play, but this one could be excellent