Thrall

Thrall is a 2005 game by L. Lynn Smith, published online.

The game is played on the following hexagonal tiling:

Each player has one piece, and there are enough wall pieces on reserve.

Rules:

• Initially, players drop their respective pieces on an empty hexagon
• On his turn, first the player slides his piece over a line of empty hexes, then places a wall piece on an empty triangle
• pieces cannot move between two occupied adjacent triangles
• Wins the player that stalemates the adversary
  

In the following position, White is winning because he enclosed the black piece is a smaller area, comparing with the area his piece is confined.

There is a ZRF to play Thrall.

Dioxoid

Dioxoid is a 1982 game by Ken Totten, published at Tau-10 Games.

The game is supposed to represent an oxygen molecule (O₂) where the large circles are the nuclei of the two oxygen atoms.

The rules:

• Setup: each player places his eight pieces (called electrons) in the marked double circles.
• On his turn, the player moves a friendly electron to an empty circle.
• If an electron moves or bounces to a circle adjacent to two other electrons, those must bounce away from the first (moving to adjacent empty circles in the opposite direction).
• If an electron moves or bounces to a circle adjacent to another electron that cannot bounce (e.g., is at the edge or near a nucleus), then it is the first electron that must bounce away in the opposite direction.
• These bounces might produce a chain reaction, bouncing more and more electrons until all stabilize.
• Ko rule: a move cannot repeat the position of the moving player's previous turn.
  
• The player that first move his electrons to the adversary's double circles wins the game.
• However, if the other player can finish in the next turn, while also being the player that started second, then the game is a draw.
  

note: the rules are not specific to where the bounced electrons should go to. But considering the chemical metaphor, and the rules stating that a piece at the edge cannot be bounced, I assume the bounce must be in the opposite direction of the moving electron.

NoGo

NoGo is a 2005 game by John Moore.

This is a game using the concepts and rules of Go, with some simplifications.

Rules:

• On her turn, the player drops a friendly piece on an empty intersection such that all existing groups of pieces (of either color) have, at least, one liberty (so, no captures or suicides are allowed)
• Wins the last player to move

Black moved last; there is no valid drop left,
so Black wins the match

This is a game that can be analyzed by the tools of Combinatorial Game Theory. The game can be split in a sum of games, when parts of the board no longer interact. For example, using a one-dimensional NoGo, the game o..xxo..xx can be split and simplified by two (in this case equal) subgames: o..x and o..x; this type of property is crucial to computing large game positions.

Moore initially called the game Anti-Atari Go at Sensei's Library. The name No Go meant, back then, another different go variant: After a player has made a move, his opponent may refuse it, and he must make another one. The opponent may not object to this second move (this variant is now known as Forced Takeback Go at Sensei's Library).

There's a ZRF and a Ludii to play the game.

Megiddo

Megiddo is 1985 game by Steve Baldwin, associated with several different publishers.

The board is made of six concentric rings under a central six-point start. There are 36 pieces of three different colors (the third color is for the three-player version):

• Each player, on her turn, drops a friendly piece on an empty circle.
• Captures are custodian: if a piece is dropped, and there are two enemy pieces and then a friendly piece, all in the same direction, then the two enemy pieces are captured, and replaced by two friendly pieces.
• The allowed directions are (a) in the same circle, (b) in the same line, (c) making a spiral on concentric circles (cf. next example)

• Captures can occur in multiple directions at the same time
• Also, captures create a chain reaction: the new pieces that replace the captured ones might produce new captures, and so on. But notice that first all multiple captures must be executed before considering chain reactions.
  
• Pieces are always captured in pairs.
  
• Wins the player that either (a) captures six enemy stones, or (b) makes one of the three winning six-piece patterns, named radial, circular, and spiral:

The rules propose a multi-match game until one player reaches 36 points:

• Winning with a winning pattern: 6 points
• Any extra winning pattern: 12 points
• Each captured piece: 1 point
  

The rules also mention a 'Cleopatra' variation: the typical custodian capture does not apply if a player drops a piece between two enemy pieces, rule which the game follows. In Cleopatra, dropping a piece inside will capture the pieces on the extremes:

Here are some tips from the original rules:

The game is a variant of Pente (which itself is an iteration of Gomoku-ninuki). The fact that there are three very different types of direction (radial, circular and spiral) removes clarity to the game. Unless players are attentive, they will miss captures and even winning patterns.

Unlike Pente, it is easy to start using pieces at the edge, which have the advantage of being harder to capture. I'm not sure if this is good or bad, but it is an important feature in this game. The tips mention 'taboo points', places where a player has a winning threat if the adversary plays there, which is something common in the moku family. Matches will converge into a cold phase, where the first player forced to play in one of those points, immediately loses the game.

A review on GAMES #67:

Intermezzo

Intermezzo is a 1993 game by Reiner Knizia, published in Spielbox magazine.

The game is played on 9x9 or 9x10 board initially empty. Each player has 33 pieces.

Rules:

• On her turn, the player either:
• drops a friendly piece on an empty square
• calls an intermezzo on a friendly piece: then all horizontal and vertical lines of empty squares between that piece and other friendly pieces, are occupied with new friendly pieces
• Wins the player that places all her stones on board

This position was shown in the original article:

after 12 moves, Black makes the first intermezzo on piece [1]

This is a pencil & paper game, no need for physical pieces to enjoy some matches.

The Spielbox article (in German):

The Game of Passo

The Game of Passo is a 1919 game by Leonard Budd Gaylor, which was self-published.

The game is played on a Checkers board, so only the pieces were sold,

Each player has ten pieces and one ball. The pieces are concave on top and can hold the ball.

This is the initial setup:

The balls are placed at e1 and d8.

• The player, on his turn, either (a) moves one friendly piece, or (b) passes his ball to another friendly piece in moving range (assuming it didn't have the ball).
• A piece without the ball can move like the Chess Queen.
• A piece with the ball can move one step diagonally (forwards or backwards) .
• There are no captures.
  
• Wins the player that either moves his ball to his last row, or surrounds the enemy ball such that it cannot be passed.
• If a player blockades all access to his first row, on his half of the board, he loses the game.

I find it interesting that the rules acknowledge an obvious drawish strategy of blocking all ways to pass through. They still leave that possibility in the opponent's area, which seems fair, since it is quite difficult to achieve that. The rules feel quite modern, despite the game is now a century old.

A rule page from that time:

The game was patented as US1363769 in 1920. Here's the visual description of the two types of pieces:

More about the game and the author in AGPI Quarterly volume 8 [1].