diff --git a/domain/src/main/kotlin/ch/dissem/yaep/domain/GameCell.kt b/domain/src/main/kotlin/ch/dissem/yaep/domain/GameCell.kt
new file mode 100644
index 0000000..9b7b9e9
--- /dev/null
+++ b/domain/src/main/kotlin/ch/dissem/yaep/domain/GameCell.kt
@@ -0,0 +1,14 @@
+package ch.dissem.yaep.domain
+
+class GameCell<C : ItemClass<C>>(
+    var selection: Item<C>?,
+    val solution: Item<C>,
+    val options: MutableList<Item<C>>
+)
+//{
+//    val options = options.toMutableStateList()
+//    var selection by mutableStateOf(selection)
+//}
+
+fun <C : ItemClass<C>> GameCell<C>?.mayBe(item: Item<C>) =
+    this != null && (selection == item || (selection == null && options.contains(item)))
diff --git a/domain/src/main/kotlin/ch/dissem/yaep/domain/GameRow.kt b/domain/src/main/kotlin/ch/dissem/yaep/domain/GameRow.kt
new file mode 100644
index 0000000..32d8808
--- /dev/null
+++ b/domain/src/main/kotlin/ch/dissem/yaep/domain/GameRow.kt
@@ -0,0 +1,14 @@
+package ch.dissem.yaep.domain
+
+class GameRow<C : ItemClass<C>>(
+    val category: ItemClassCompanion<C>,
+    val options: List<Item<C>>,
+    val cells: List<GameCell<C>>
+) : List<GameCell<C>> by cells {
+    fun indexOf(element: C) = indexOfFirst { it.selection?.itemType == element }
+
+    fun updateOptions() {
+        val selections = mapNotNull { it.selection }
+        forEach { it.options.removeAll(selections) }
+    }
+}
diff --git a/domain/src/main/kotlin/ch/dissem/yaep/domain/Grid.kt b/domain/src/main/kotlin/ch/dissem/yaep/domain/Grid.kt
new file mode 100644
index 0000000..1349a5c
--- /dev/null
+++ b/domain/src/main/kotlin/ch/dissem/yaep/domain/Grid.kt
@@ -0,0 +1,41 @@
+package ch.dissem.yaep.domain
+
+class Grid(
+    val rows: List<GameRow<ItemClass<*>>>
+) : List<GameRow<ItemClass<*>>> by rows {
+
+    fun <C : ItemClass<C>> indexOf(element: C): Int {
+        return this[element.companion]
+            .indexOfFirst { it.selection?.itemType == element }
+    }
+
+    operator fun <C : ItemClass<C>> get(itemType: ItemClassCompanion<C>): GameRow<C> {
+        @Suppress("UNCHECKED_CAST")
+        return rows.first { it.category == itemType } as GameRow<C>
+    }
+
+    operator fun <C : ItemClass<C>> get(item: Item<C>): GameCell<C> {
+        return this[item.itemType.companion].first { it.selection == item }
+    }
+
+    override fun toString(): String {
+        return rows.map { row -> row.map { it.selection?.symbol ?: "  " }.joinToString("") }
+            .joinToString("\n")
+    }
+}
+
+fun List<List<Item<ItemClass<*>>>>.toGrid() = Grid(
+    map { row ->
+        GameRow(
+            category = row.first().itemType.companion,
+            options = row,
+            cells = row.map {
+                GameCell(
+                    selection = null,
+                    solution = it,
+                    options = row.toMutableList()
+                )
+            }
+        )
+    }
+)
diff --git a/domain/src/main/kotlin/ch/dissem/yaep/domain/Item.kt b/domain/src/main/kotlin/ch/dissem/yaep/domain/Item.kt
new file mode 100644
index 0000000..87ae858
--- /dev/null
+++ b/domain/src/main/kotlin/ch/dissem/yaep/domain/Item.kt
@@ -0,0 +1,23 @@
+package ch.dissem.yaep.domain
+
+
+class Item<C : ItemClass<C>>(
+    val itemType: C,
+    val symbol: String = itemType.symbols.random()
+) {
+    constructor(itemType: C) : this(itemType, itemType.symbols.random())
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other !is Item<*>) return false
+        return itemType == other.itemType
+    }
+
+    override fun hashCode(): Int {
+        return itemType.hashCode()
+    }
+
+    override fun toString(): String {
+        return itemType.toString() + symbol
+    }
+}
diff --git a/domain/src/main/kotlin/ch/dissem/yaep/domain/grid.kt b/domain/src/main/kotlin/ch/dissem/yaep/domain/grid.kt
deleted file mode 100644
index c17dbbd..0000000
--- a/domain/src/main/kotlin/ch/dissem/yaep/domain/grid.kt
+++ /dev/null
@@ -1,88 +0,0 @@
-package ch.dissem.yaep.domain
-
-class GameRow<C : ItemClass<C>>(
-    val category: ItemClassCompanion<C>,
-    val options: List<Item<C>>,
-    val cells: List<GameCell<C>>
-) : List<GameCell<C>> by cells {
-    fun indexOf(element: C) = indexOfFirst { it.selection?.itemType == element }
-
-    fun updateOptions() {
-        val selections = mapNotNull { it.selection }
-        forEach { it.options.removeAll(selections) }
-    }
-}
-
-class Grid(
-    val rows: List<GameRow<ItemClass<*>>>
-) : List<GameRow<ItemClass<*>>> by rows {
-
-    fun <C : ItemClass<C>> indexOf(element: C): Int {
-        return this[element.companion]
-            .indexOfFirst { it.selection?.itemType == element }
-    }
-
-    operator fun <C : ItemClass<C>> get(itemType: ItemClassCompanion<C>): GameRow<C> {
-        @Suppress("UNCHECKED_CAST")
-        return rows.first { it.category == itemType } as GameRow<C>
-    }
-
-    operator fun <C : ItemClass<C>> get(item: Item<C>): GameCell<C> {
-        return this[item.itemType.companion].first { it.selection == item }
-    }
-
-    override fun toString(): String {
-        return rows.map { row -> row.map { it.selection?.symbol ?: "  " }.joinToString("") }
-            .joinToString("\n")
-    }
-}
-
-fun List<List<Item<ItemClass<*>>>>.toGrid() = Grid(
-    map { row ->
-        GameRow(
-            category = row.first().itemType.companion,
-            options = row,
-            cells = row.map {
-                GameCell(
-                    selection = null,
-                    solution = it,
-                    options = row.toMutableList()
-                )
-            }
-        )
-    }
-)
-
-class GameCell<C : ItemClass<C>>(
-    var selection: Item<C>?,
-    val solution: Item<C>,
-    val options: MutableList<Item<C>>
-)
-//{
-//    val options = options.toMutableStateList()
-//    var selection by mutableStateOf(selection)
-//}
-
-fun <C : ItemClass<C>> GameCell<C>?.mayBe(item: Item<C>) =
-    this != null && (selection == item || (selection == null && options.contains(item)))
-
-class Item<C : ItemClass<C>>(
-    val itemType: C,
-    val symbol: String = itemType.symbols.random()
-) {
-    constructor(itemType: C) : this(itemType, itemType.symbols.random())
-
-    override fun equals(other: Any?): Boolean {
-        if (this === other) return true
-        if (other !is Item<*>) return false
-        return itemType == other.itemType
-    }
-
-    override fun hashCode(): Int {
-        return itemType.hashCode()
-    }
-
-    override fun toString(): String {
-        return itemType.toString() + symbol
-    }
-}
\ No newline at end of file