diff --git a/src/shared/game-variants/capture-the-castle/capture-the-castle.ts b/src/shared/game-variants/capture-the-castle/capture-the-castle.ts
new file mode 100644
index 0000000..c1bff49
--- /dev/null
+++ b/src/shared/game-variants/capture-the-castle/capture-the-castle.ts
@@ -0,0 +1,52 @@
+import { CurrentOutcome, GameRules, SquareState } from "../../datatypes/types.ts";
+
+// Simple rules: whoever occupies all the squares passed as a parameter, wins
+// This ruleset is only used in tests currently
+export const createRulesForSquares = (...squares: [number, number][]): GameRules => ({
+  getBoardOutcome: (board) => {
+    let hasX = false;
+    let hasO = false;
+    let hasUnoccupied = false;
+
+    for (const [row, column] of squares) {
+      const state = board.get(row, column);
+      switch (state) {
+        case SquareState.X:
+          hasX = true;
+          break;
+        case SquareState.O:
+          hasO = true;
+          break;
+        case SquareState.Unoccupied:
+          hasUnoccupied = true;
+          break;
+      }
+    }
+
+    if (hasX && hasO) {
+      return CurrentOutcome.Draw;
+    }
+
+    if (hasUnoccupied) {
+      return CurrentOutcome.Undecided;
+    }
+
+    if (hasX) {
+      return CurrentOutcome.WinX;
+    }
+
+    if (hasO) {
+      return CurrentOutcome.WinO;
+    }
+
+    // Special case: if there are no X, O or unoccupied squares,
+    // this means that the squares list is empty,
+    // and in this case we only want to decide the board as Draw when it's full
+    // and no moves can be made.
+    if (board.serialize().includes("_")) {
+      return CurrentOutcome.Undecided;
+    }
+
+    return CurrentOutcome.Draw;
+  },
+});
diff --git a/src/shared/gameplay/solver.spec.ts b/src/shared/gameplay/solver.spec.ts
index 47df26e..4f907d6 100644
--- a/src/shared/gameplay/solver.spec.ts
+++ b/src/shared/gameplay/solver.spec.ts
@@ -1,7 +1,8 @@
 import t, { type Test } from "tap";
 
-import { CurrentOutcome, ExpectedOutcome, FinalOutcome, GameRules, Player, SquareState } from "../datatypes/types.ts";
+import { ExpectedOutcome, FinalOutcome, Player } from "../datatypes/types.ts";
 import { computeAllSolutions, getPreferredNextOutcome } from "./solver.ts";
+import { createRulesForSquares } from "../game-variants/capture-the-castle/capture-the-castle.ts";
 
 void t.test("getPreferredNextOutcome", async (t) => {
   const nextOutcomes: ExpectedOutcome[] = [
@@ -83,56 +84,6 @@ void t.test("getPreferredNextOutcome", async (t) => {
 });
 
 void t.test("computeAllSolutions", async (t) => {
-  // Simple rules: whoever occupies all the squares passed as a parameter, wins
-  const createRulesForSquares = (...squares: [number, number][]): GameRules => ({
-    getBoardOutcome: (board) => {
-      let hasX = false;
-      let hasO = false;
-      let hasUnoccupied = false;
-
-      for (const [row, column] of squares) {
-        const state = board.get(row, column);
-        switch (state) {
-          case SquareState.X:
-            hasX = true;
-            break;
-          case SquareState.O:
-            hasO = true;
-            break;
-          case SquareState.Unoccupied:
-            hasUnoccupied = true;
-            break;
-        }
-      }
-
-      if (hasX && hasO) {
-        return CurrentOutcome.Draw;
-      }
-
-      if (hasUnoccupied) {
-        return CurrentOutcome.Undecided;
-      }
-
-      if (hasX) {
-        return CurrentOutcome.WinX;
-      }
-
-      if (hasO) {
-        return CurrentOutcome.WinO;
-      }
-
-      // Special case: if there are no X, O or unoccupied squares,
-      // this means that the squares list is empty,
-      // and in this case we only want to decide the board as Draw when it's full
-      // and no moves can be made.
-      if (board.serialize().includes("_")) {
-        return CurrentOutcome.Undecided;
-      }
-
-      return CurrentOutcome.Draw;
-    },
-  });
-
   const checkSolutionsComplete = (
     t: Test,
     rows: number,