diff --git a/src/main/kotlin/rps/App.kt b/src/main/kotlin/rps/App.kt
deleted file mode 100644
index ce187fa..0000000
--- a/src/main/kotlin/rps/App.kt
+++ /dev/null
@@ -1,5 +0,0 @@
-package rps
-
-fun main() {
-    println("Hello, world")
-}
diff --git a/src/main/kotlin/rps/Game.kt b/src/main/kotlin/rps/Game.kt
new file mode 100644
index 0000000..2606fe5
--- /dev/null
+++ b/src/main/kotlin/rps/Game.kt
@@ -0,0 +1,22 @@
+package rps
+
+fun main() {
+  println("Hello, world")
+}
+
+/** A possible move in a game of rock-paper-scissors. */
+enum class Move {
+  ROCK,
+  PAPER,
+  SCISSORS
+}
+
+// purposely not calling this Result to avoid confusion with kotlin.Result and similar
+enum class Outcome {
+  WIN,
+  DRAW,
+  LOSS
+}
+
+/** Determine the [Outcome] of [first] vs [second] from the perspective of [first]. */
+fun determineOutcome(first: Move, second: Move): Outcome = TODO()
\ No newline at end of file
diff --git a/src/test/kotlin/rps/AppTest.kt b/src/test/kotlin/rps/AppTest.kt
deleted file mode 100644
index be22bdf..0000000
--- a/src/test/kotlin/rps/AppTest.kt
+++ /dev/null
@@ -1,14 +0,0 @@
-/*
- * This Kotlin source file was generated by the Gradle 'init' task.
- */
-package rps
-
-import kotlin.test.Test
-import kotlin.test.assertEquals
-
-class GameTest {
-    @Test
-    fun testAppHasAGreeting() {
-        assertEquals(2 + 2, 4)
-    }
-}
diff --git a/src/test/kotlin/rps/GameTest.kt b/src/test/kotlin/rps/GameTest.kt
new file mode 100644
index 0000000..34ebe0e
--- /dev/null
+++ b/src/test/kotlin/rps/GameTest.kt
@@ -0,0 +1,21 @@
+package rps
+
+import rps.Move.*
+import rps.Outcome.*
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class GameTest {
+  @Test
+  fun testOutcomeCalculation() {
+    val games = listOf(
+        Triple(PAPER, ROCK, WIN),
+        Triple(ROCK, PAPER, LOSS),
+        Triple(PAPER, SCISSORS, LOSS),
+        Triple(ROCK, ROCK, DRAW),
+    )
+    for ((first, second, expected) in games) {
+      assertEquals(determineOutcome(first, second), expected)
+    }
+  }
+}