diff --git a/CLI/CLI/main.swift b/CLI/CLI/main.swift
index 494613f..68cafed 100644
--- a/CLI/CLI/main.swift
+++ b/CLI/CLI/main.swift
@@ -18,7 +18,7 @@ for move in rules.validMoves(board: board) {
     print(move)
 }
 
-print("Moves for \(Player.A):")
+print("Moves for \(PieceType.A):")
 for move in rules.validMoves(board: board, for_player: .A) {
     print(move)
 }
@@ -42,7 +42,7 @@ while case .Playing(let turn) = rules.state {
         direction: .Bottom
     ) {
     case .Border(let at), .Piece(let at, _):
-        board[at] = Piece(owner: turn)
+        board[at] = Piece(type: turn)
     case .Occupied:
         fatalError("Occupied???")
     }
diff --git a/CustomTypes/Sources/CustomTypes/Display.swift b/CustomTypes/Sources/CustomTypes/Display.swift
index e1add0c..3b2b6a0 100644
--- a/CustomTypes/Sources/CustomTypes/Display.swift
+++ b/CustomTypes/Sources/CustomTypes/Display.swift
@@ -1,6 +1,6 @@
 import Model
 
-extension Player: CustomStringConvertible {
+extension PieceType: CustomStringConvertible {
     public var description: String {
         switch self {
         case .A:
@@ -17,7 +17,7 @@ extension Board: CustomStringConvertible, CustomDebugStringConvertible {
         
         for row in 0..<self.rows {
             for col in 0..<self.columns {
-                str += self[col, row]?.owner.description ?? "⚪"
+                str += self[col, row]?.type.description ?? "⚪"
             }
             
             str += "\n"
@@ -27,7 +27,7 @@ extension Board: CustomStringConvertible, CustomDebugStringConvertible {
     }
     
     public var debugDescription: String {
-        return "Board[\(self.columns)x\(self.rows), \(self.countPieces { p in p.owner == .A }) A and \(self.countPieces { p in p.owner == .B }) B pieces]"
+        return "Board[\(self.columns)x\(self.rows), \(self.countPieces { p in p.type == .A }) A and \(self.countPieces { p in p.type == .B }) B pieces]"
     }
 }
 
diff --git a/CustomTypes/Tests/CustomTypesTests/DisplayTests.swift b/CustomTypes/Tests/CustomTypesTests/DisplayTests.swift
index a9ad2d2..09d32b6 100644
--- a/CustomTypes/Tests/CustomTypesTests/DisplayTests.swift
+++ b/CustomTypes/Tests/CustomTypesTests/DisplayTests.swift
@@ -9,10 +9,10 @@ final class CustomTypesTests: XCTestCase {
             return
         }
         
-        board[1, 1] = Piece(owner: .A)
-        board[2, 1] = Piece(owner: .A)
-        board[2, 2] = Piece(owner: .A)
-        board[1, 2] = Piece(owner: .B)
+        board[1, 1] = Piece(type: .A)
+        board[2, 1] = Piece(type: .A)
+        board[2, 2] = Piece(type: .A)
+        board[1, 2] = Piece(type: .B)
         
         let text: String = board.description
         
diff --git a/Model/Sources/Model/Piece.swift b/Model/Sources/Model/Piece.swift
index 13fc00f..c455796 100644
--- a/Model/Sources/Model/Piece.swift
+++ b/Model/Sources/Model/Piece.swift
@@ -1,8 +1,8 @@
 public struct Piece : Sendable {
-    public let owner: Player
+    public let type: PieceType
     
     // Required for public visibility
-    public init(owner: Player) {
-        self.owner = owner
+    public init(type: PieceType) {
+        self.type = type
     }
 }
diff --git a/Model/Sources/Model/PieceType.swift b/Model/Sources/Model/PieceType.swift
new file mode 100644
index 0000000..014c47e
--- /dev/null
+++ b/Model/Sources/Model/PieceType.swift
@@ -0,0 +1,3 @@
+public enum PieceType: CaseIterable, Sendable {
+    case A, B
+}
diff --git a/Model/Sources/Model/Player.swift b/Model/Sources/Model/Player.swift
deleted file mode 100644
index 67f6872..0000000
--- a/Model/Sources/Model/Player.swift
+++ /dev/null
@@ -1,3 +0,0 @@
-public enum Player: CaseIterable, Sendable {
-    case A, B
-}
diff --git a/Model/Sources/Model/Rules/FourInARowRules.swift b/Model/Sources/Model/Rules/FourInARowRules.swift
index 15d7305..c996245 100644
--- a/Model/Sources/Model/Rules/FourInARowRules.swift
+++ b/Model/Sources/Model/Rules/FourInARowRules.swift
@@ -63,14 +63,14 @@ public struct FourInARowRules: Rules {
     }
 
     public func validMoves(board: Board) -> [Move] {
-        return Player.allCases.flatMap({
+        return PieceType.allCases.flatMap({
             player in self.validMoves(board: board, for_player: player).map({
                 action in Move(player: player, action: action)
             })
         })
     }
 
-    public func validMoves(board: Board, for_player player: Player) -> [Move.Action] {
+    public func validMoves(board: Board, for_player player: PieceType) -> [Move.Action] {
         var moves: [Move.Action] = [];
 
         for c in 0..<board.columns {
@@ -110,7 +110,7 @@ public struct FourInARowRules: Rules {
             } else if board.countPieces() == board.columns * board.rows {
                 self.state = .Finished(winner: nil)
             } else {
-                let next: Player = switch move.player {
+                let next: PieceType = switch move.player {
                 case .A: .B
                 case .B: .A
                 }
@@ -122,7 +122,7 @@ public struct FourInARowRules: Rules {
     }
     
     internal static func countMaxRow(center: Coords, board: Board) -> Int {
-        guard let of = board[center]?.owner else { return 0 }
+        guard let of = board[center]?.type else { return 0 }
         
         var maxLength = 0
         // For each "axis" (described as one direction)
@@ -135,7 +135,7 @@ public struct FourInARowRules: Rules {
                 
                 while true {
                     pos = Coords(pos.col + dc, pos.row + dr)
-                    if !board.isInBounds(pos) || board[pos]?.owner != of { break }
+                    if !board.isInBounds(pos) || board[pos]?.type != of { break }
                     length += 1
                 }
             }
diff --git a/Model/Sources/Model/Rules/Move.swift b/Model/Sources/Model/Rules/Move.swift
index 01db9b7..97b3f62 100644
--- a/Model/Sources/Model/Rules/Move.swift
+++ b/Model/Sources/Model/Rules/Move.swift
@@ -1,8 +1,8 @@
 public struct Move: Equatable {
-    public let player: Player
+    public let player: PieceType
     public let action: Action
     
-    public init(player: Player, action: Action) {
+    public init(player: PieceType, action: Action) {
         self.player = player
         self.action = action
     }
diff --git a/Model/Sources/Model/Rules/Rules.swift b/Model/Sources/Model/Rules/Rules.swift
index 6937d79..b55fe59 100644
--- a/Model/Sources/Model/Rules/Rules.swift
+++ b/Model/Sources/Model/Rules/Rules.swift
@@ -11,13 +11,13 @@ public protocol Rules {
 
     func validMoves(board: Board) -> [Move]
 
-    func validMoves(board: Board, for_player player: Player) -> [Move.Action]
+    func validMoves(board: Board, for_player player: PieceType) -> [Move.Action]
 
     mutating func onMoveDone(move: Move, board: Board) -> Void
 }
 
 public enum GameState: Equatable {
-    case Playing(turn: Player)
+    case Playing(turn: PieceType)
 
-    case Finished(winner: Player?)
+    case Finished(winner: PieceType?)
 }
diff --git a/Model/Sources/Model/Rules/TicTacToeRules.swift b/Model/Sources/Model/Rules/TicTacToeRules.swift
index 3d5a61e..03c9195 100644
--- a/Model/Sources/Model/Rules/TicTacToeRules.swift
+++ b/Model/Sources/Model/Rules/TicTacToeRules.swift
@@ -16,8 +16,8 @@ public struct TicTacToeRules: Rules {
     }
     
     public func isValid(board: Board) -> Bool {
-        abs(board.countPieces(filter: { p in p.owner == .A }) -
-            board.countPieces(filter: { p in p.owner == .B })) <= 1
+        abs(board.countPieces(filter: { p in p.type == .A }) -
+            board.countPieces(filter: { p in p.type == .B })) <= 1
     }
     
     public func isValid(board: Board, move: Move) -> Bool {
@@ -38,15 +38,15 @@ public struct TicTacToeRules: Rules {
         return self.validMoves(board: board, for_player: player).map { Move(player: player, action: $0) }
     }
     
-    private static func nextPlayer(board: Board) -> Player {
-        if board.countPieces(filter: { p in p.owner == .A }) > board.countPieces(filter: { p in p.owner == .B }) {
+    private static func nextPlayer(board: Board) -> PieceType {
+        if board.countPieces(filter: { p in p.type == .A }) > board.countPieces(filter: { p in p.type == .B }) {
             .B
         } else {
             .A
         }
     }
     
-    public func validMoves(board: Board, for_player player: Player) -> [Move.Action] {
+    public func validMoves(board: Board, for_player player: PieceType) -> [Move.Action] {
         var moves: [Move.Action] = []
         
         for col in 0..<board.columns {
@@ -72,7 +72,7 @@ public struct TicTacToeRules: Rules {
         } else if board.countPieces() == board.columns * board.rows {
             self.state = .Finished(winner: nil)
         } else {
-            let next: Player = switch move.player {
+            let next: PieceType = switch move.player {
             case .A: .B
             case .B: .A
             }
diff --git a/Model/Tests/ModelTests/EmptyBoardTests.swift b/Model/Tests/ModelTests/EmptyBoardTests.swift
index f26b158..2330321 100644
--- a/Model/Tests/ModelTests/EmptyBoardTests.swift
+++ b/Model/Tests/ModelTests/EmptyBoardTests.swift
@@ -32,7 +32,7 @@ final class EmptyBoardTests: XCTestCase {
     func testCustomSubscript() throws {
         for r in 0..<board.rows {
             for c in 0..<board.columns {
-                for p: Player in [.A, .B] {
+                for p: PieceType in [.A, .B] {
                     try self.setUpWithError()
                     
                     try self._testCustomSubscript(at: Coords(c, r), player: p)
@@ -43,19 +43,19 @@ final class EmptyBoardTests: XCTestCase {
         }
     }
     
-    private func _testCustomSubscript(at: Coords, player: Player) throws {
-        board[at] = Piece(owner: player)
+    private func _testCustomSubscript(at: Coords, player: PieceType) throws {
+        board[at] = Piece(type: player)
         
-        XCTAssertEqual(board[at]?.owner, player)
+        XCTAssertEqual(board[at]?.type, player)
     }
     
     func testCounts() throws {
-        board[1, 2] = Piece(owner: .B)
-        board[0, 2] = Piece(owner: .A)
-        board[1, 1] = Piece(owner: .A)
+        board[1, 2] = Piece(type: .B)
+        board[0, 2] = Piece(type: .A)
+        board[1, 1] = Piece(type: .A)
         
-        XCTAssertEqual(board.countPieces { piece in piece.owner == .A }, 2)
-        XCTAssertEqual(board.countPieces { piece in piece.owner == .B }, 1)
+        XCTAssertEqual(board.countPieces { piece in piece.type == .A }, 2)
+        XCTAssertEqual(board.countPieces { piece in piece.type == .B }, 1)
     }
     
     func testInsertsSides() throws {
@@ -129,9 +129,9 @@ final class EmptyBoardTests: XCTestCase {
             ] {
                 // ensure it works with any player
                 board[Coords(pair: pos)] = if (pos.0 + pos.1) & 1 == 1 {
-                    Piece(owner: .A)
+                    Piece(type: .A)
                 } else {
-                    Piece(owner: .B)
+                    Piece(type: .B)
                 }
             }
             
diff --git a/Model/Tests/ModelTests/FilledBoardTests.swift b/Model/Tests/ModelTests/FilledBoardTests.swift
index 389bfe2..c665aec 100644
--- a/Model/Tests/ModelTests/FilledBoardTests.swift
+++ b/Model/Tests/ModelTests/FilledBoardTests.swift
@@ -15,9 +15,9 @@ final class FilledBoardTests: XCTestCase {
         for row in 0..<board.rows {
             for col in 0..<board.columns {
                 board[col, row] = if (row & 1) == 1 {
-                    Piece(owner: .A)
+                    Piece(type: .A)
                 } else {
-                    Piece(owner: .B)
+                    Piece(type: .B)
                 }
             }
         }
diff --git a/Model/Tests/ModelTests/Rules/FourInARowRulesTests.swift b/Model/Tests/ModelTests/Rules/FourInARowRulesTests.swift
index c32c0f7..0177389 100644
--- a/Model/Tests/ModelTests/Rules/FourInARowRulesTests.swift
+++ b/Model/Tests/ModelTests/Rules/FourInARowRulesTests.swift
@@ -37,7 +37,7 @@ final class FourInARowRulesTests: XCTestCase {
     }
     
     func testMovesOfPlayerAreValid() throws {
-        for player in Player.allCases {
+        for player in PieceType.allCases {
             try self.setUpWithError()
             
             try self._testMovesOfPlayerAreValid(player: player)
@@ -46,7 +46,7 @@ final class FourInARowRulesTests: XCTestCase {
         }
     }
     
-    private func _testMovesOfPlayerAreValid(player: Player) throws {
+    private func _testMovesOfPlayerAreValid(player: PieceType) throws {
         for action in self.rules.validMoves(board: self.board, for_player: player) {
             rules.state = .Playing(turn: player)
             XCTAssertTrue(self.rules.isValid(board: board, move: Move(player: player, action: action)), "\(action)")
@@ -55,7 +55,7 @@ final class FourInARowRulesTests: XCTestCase {
     
     func testOnMoveDone() {
         let coord = Coords(1, board.rows - 1)
-        board[coord] = Piece(owner: .A)
+        board[coord] = Piece(type: .A)
         let move = Move(player: .A, action: .InsertOnSide(side: .Top, offset: 1))
         self.rules.onMoveDone(move: move, board: self.board)
         
@@ -64,16 +64,16 @@ final class FourInARowRulesTests: XCTestCase {
     }
     
     func testOnMoveDoneDraw() {
-        board[0, 0] = Piece(owner: .A)
-        board[1, 0] = Piece(owner: .A)
-        board[2, 0] = Piece(owner: .B)
-        board[0, 1] = Piece(owner: .B)
-        board[1, 1] = Piece(owner: .B)
-        board[2, 1] = Piece(owner: .A)
-        board[0, 2] = Piece(owner: .A)
-        board[1, 2] = Piece(owner: .A)
+        board[0, 0] = Piece(type: .A)
+        board[1, 0] = Piece(type: .A)
+        board[2, 0] = Piece(type: .B)
+        board[0, 1] = Piece(type: .B)
+        board[1, 1] = Piece(type: .B)
+        board[2, 1] = Piece(type: .A)
+        board[0, 2] = Piece(type: .A)
+        board[1, 2] = Piece(type: .A)
         
-        board[2, 2] = Piece(owner: .B)
+        board[2, 2] = Piece(type: .B)
         
         XCTAssertTrue(rules.isValid(board: board))
         
@@ -85,15 +85,15 @@ final class FourInARowRulesTests: XCTestCase {
     }
     
     func testOnMoveDoneWin() {
-        board[0, 0] = Piece(owner: .A)
-        board[1, 0] = Piece(owner: .A)
-        board[2, 0] = Piece(owner: .A) //
-        board[0, 1] = Piece(owner: .B)
-        board[1, 1] = Piece(owner: .B)
-        board[2, 1] = Piece(owner: .A)
-        board[0, 2] = Piece(owner: .A)
-        board[1, 2] = Piece(owner: .A)
-        board[2, 2] = Piece(owner: .B)
+        board[0, 0] = Piece(type: .A)
+        board[1, 0] = Piece(type: .A)
+        board[2, 0] = Piece(type: .A) //
+        board[0, 1] = Piece(type: .B)
+        board[1, 1] = Piece(type: .B)
+        board[2, 1] = Piece(type: .A)
+        board[0, 2] = Piece(type: .A)
+        board[1, 2] = Piece(type: .A)
+        board[2, 2] = Piece(type: .B)
         
         XCTAssertTrue(rules.isValid(board: board))
         
@@ -118,15 +118,15 @@ final class FourInARowRulesTests: XCTestCase {
             // AAA
             // BAB
             // BBA
-            board[0, 0] = Piece(owner: .A)
-            board[1, 0] = Piece(owner: .A)
-            board[2, 0] = Piece(owner: .A)
-            board[0, 1] = Piece(owner: .B)
-            board[1, 1] = Piece(owner: .A)
-            board[2, 1] = Piece(owner: .B)
-            board[0, 2] = Piece(owner: .B)
-            board[1, 2] = Piece(owner: .B)
-            board[2, 2] = Piece(owner: .A)
+            board[0, 0] = Piece(type: .A)
+            board[1, 0] = Piece(type: .A)
+            board[2, 0] = Piece(type: .A)
+            board[0, 1] = Piece(type: .B)
+            board[1, 1] = Piece(type: .A)
+            board[2, 1] = Piece(type: .B)
+            board[0, 2] = Piece(type: .B)
+            board[1, 2] = Piece(type: .B)
+            board[2, 2] = Piece(type: .A)
             
             self._testCountMaxRow(coords: coords, expected: expected)