Terrace: Fix Assassination rules

Author: Perlkonig

locales/en/apgames.json

@@ -206,7 +206,7 @@
         "tafl": "The variant names are in the format {ruleset}-{board size}-{initial layout}-{optional: starting player}. For example, 'linnaean-9x9-tcross-w' is the linnaean rules on a 9x9 board with T-cross setup, and the starting player is the defenders. If starting player is not mentioned, then attackers start.",
         "taiji": "Moves are done with two clicks. The first tile you place is always the light one, and then the dark one.",
         "tbt": "When it's your turn, you will see the die you have to work with, but once your move is complete, the die will reroll. Exploration is not helpful because the die roll is not finalized until after the move is submitted. As you scroll back through the game history, the die you see is for the *next* turn. The die used to make the move you're seeing is displayed below the board.",
-        "terrace": "The Assassination variant is described in [this BGG thread](https://boardgamegeek.com/thread/551125/variant-for-more-aggressive-less-drawish-play), summarized below:\n\n- Up straight, you must be larger or the king can assassinate a largest-size piece.\n\n- Same level (adjacent only), you must be at least the same size.\n\n- Down diagonal, you must be smaller.",
+        "terrace": "The Assassination variant is described in [this BGG thread](https://boardgamegeek.com/thread/551125/variant-for-more-aggressive-less-drawish-play), summarized below:\n\n- Up straight, you must be larger or a smallest-size piece can assassinate a largest-size piece.\n\n- Same level (orthogonally adjacent only), you must be at least the same size.\n\n- Down diagonal, you may be one rank smaller.",
         "toguz": "Depicting state changes in sowing games is challenging. The initial chosen pit is marked, as is any capture. Small numbers appear to show the change in the number of stones in each pit. If you believe you have encountered a bug, please let us know in Discord.",
         "tumbleweed": "A space is claimed by a player if they have a piece on it, or if they have the majority of the line of sights to it. The score is the number of territory own by each player. The game ends when both players pass in succession. If there is no change in score for 20 plies, the game also ends.",
         "twixt": "The notation is based on Hansel notation at <http://www.ibiblio.org/twixtpuzzles/>. Some modifications are that link removal specifically specifies the link direction, and commas separate the moves. To add/remove links, click on the pegs between them. You can also remove a link by clicking on the line itself.",
@@ -4374,7 +4374,7 @@
             "TOO_SHORT": "The stack at {{where}} is too short (it needs at least {{roll}} pieces)."
         },
         "terrace": {
-            "BAD_CAPTURE_ranked": "All captures must be adjacent. When capturing straight up, you must be larger (except that your king may assassinate a largest size piece). When capturing same level, you must be at least the same size. When capturing diagonally down, you must be smaller.",
+            "BAD_CAPTURE_ranked": "All captures must be adjacent. When capturing straight up, you must be larger (except that a smallest-size may assassinate a largest-size piece). When capturing same level, you must be at least the same size. When capturing diagonally down, you may be one rank smaller.",
             "BAD_CAPTURE_standard": "You may only capture a piece your size or smaller, diagonally down.",
             "INITIAL_INSTRUCTIONS": "Select one of your pieces to move.",
             "MOVE_DOWN": "You may only move straight down and only one level at a time.",

src/games/terrace.ts

@@ -359,11 +359,11 @@ export class TerraceGame extends GameBase {
                 const capUp = gOrth.neighbours(piece.location).filter(cell => this.board.has(cell) && gOrth.elevation(cell) === thisElev + 1 && this.board.get(cell)!.size < piece.size);
                 // same level, I must be at least same size and orthogonally adjacent
                 const capSame = gOrth.neighbours(piece.location).filter(cell => this.board.has(cell) && gOrth.elevation(cell) === thisElev && this.board.get(cell)!.size <= piece.size);
-                // down diagonal, I must be at least 1 size smaller
-                const capDown = gDiag.neighbours(piece.location).filter(cell => this.board.has(cell) && gDiag.elevation(cell) === thisElev - 1 && this.board.get(cell)!.size > piece.size);
-                // up straight, my king attacking a largest piece
+                // down diagonal, I may be at most 1 size smaller
+                const capDown = gDiag.neighbours(piece.location).filter(cell => this.board.has(cell) && gDiag.elevation(cell) === thisElev - 1 && piece.size >= this.board.get(cell)!.size - 1);
+                // up straight, smallest piece attacking a largest piece
                 const largest: size = this.variants.includes("board-8") ? 4 : 3;
-                const assassinations = gOrth.neighbours(piece.location).filter(cell => this.board.has(cell) && gOrth.elevation(cell) === thisElev + 1 && this.board.get(cell)!.size === largest && piece.royal);
+                const assassinations = gOrth.neighbours(piece.location).filter(cell => this.board.has(cell) && gOrth.elevation(cell) === thisElev + 1 && this.board.get(cell)!.size === largest && piece.size === 1);
 
                 for (const cell of [...capUp, ...capSame, ...capDown, ...assassinations]) {
                     // different notation for canibalizing