Rawlsian Chess

When I was a kid, my mom loved to watch X-Files. One evening I walked by and briefly saw a scene where Mulder and Scully discover a dead man lying on the floor, cut in half at the waist. I couldn't sleep the whole night, as I was sure he was lying on the floor beside my bed, and I had to keep checking to make sure he wasn't.

In that episode, it turns out that this man was killed by an escaped convict named Wilson "Pinker" Rawls, who had gained the ability to pass through matter that conducts electricity, including people, destroying the matter and killing the people in the process.

Rawlsian Chess allows players to move through any number of their own pieces at any time, killing them in the process.

Note that:

• You may put your opponent in check through your own pieces (which doesn't kill them, since the king is just being threatened through them).
• The knight jumps to its spot, so doesn't need to pass through other pieces.
• You may land directly on your own piece, killing it.
• You may castle through your own pieces.

Decoy Chess

In Star Wars: Episode I – The Phantom Menace, Queen Amidala, played by Natalie Portman, has a decoy, played by Kiera Knightley. The real queen is on the left, and the decoy queen is on the right.

In Decoy Chess, at the start of the game each player may swap their true king with any other piece, marked with a sticker under the piece. What looks like the king is then a decoy (Kiera), while the true king (Natalie) lies elsewhere on the board. Each piece moves like the piece it actually is. For example, if the decoy king is the left bishop, then the king is actually a bishop, and moves like one, while the left bishop is actually the king, and moves like one.

A player wins when they take the other player's true king. There is no check or checkmate. The decoy king may castle as normal. Note that you may also choose not to decoy your king, i.e., to put your sticker under the king itself.

Paratrooper Chess

Thanks to Marcus Pivato for suggesting the name.

Stage 1. Each player takes turns placing (parachuting) each piece on the board—anywhere.

Stage 2. After all pieces are placed, standard chess is played, with the player who moved first in Stage 1 again moving first in Stage 2 (note that they may start in check).

The rules for Stage 2 are precisely the same as in standard chess, subject to the following.

• Pawns that start on your half of the board can be promoted upon reaching the opposite side. Pawns that start on your opponents side cannot.
• Pawns that start on the starting line can move one or two spaces ahead with their first move as usual. All other pawns can only move in the standard way.

Three Musketeers Chess

I came up with this variant in a dream. I'm surprised it worked out so nicely, as usually things in dreams seem good in the dream, but then are relatively non-sensical in real life.

Three Musketeers Chess allows players to move any of the three musketeers—the queen, knight, and bishop—all together.

If you move a queen, knight, or bishop, then you may move each of those pieces once in sequence. For example, if you move a knight, then you have the option to also move one bishop and/or the queen, one after the other, during a single turn.

Tsunami Chess

Tsunami Chess allows players to make multiple moves per turn, but the more moves they make, the more moves they give their opponent on the next turn. You can create a tsunami of moves against your opponent, but the bigger the initial wave, the bigger the subsequent wave too.

Player 1 starts with one move plus as many bonus moves as Player 2 took on the previous turn (or zero if it is the start of the game). These are Player 1's default moves. Player 1 must make all their default moves. Player 1 can then add as many additional bonus moves as they like, understanding that this adds moves to Player 2's default moves on the next turn. The same rules apply to Player 2.

Moreover:

• Each piece can only be moved once per turn.
• If your opponent can only make n legal moves on their turn, then you can only take n - 1 bonus moves on your turn.

For example, Player 1 takes their 1 default move plus 2 bonus moves. Player 2 takes their 3 default moves plus 3 bonus moves. Player 1 takes their 4 default moves plus 0 bonus moves. Player 2 takes their 1 default move plus 1 bonus move. And so on.