diff --git a/src/play.rs b/src/play.rs
index b2820b9..2c5b65f 100644
--- a/src/play.rs
+++ b/src/play.rs
@@ -33,7 +33,7 @@ pub(crate) fn toggle_selected(
     }
 }
 
-pub(crate) fn check_set(trigger: Trigger<Pointer<Click>>, query: Query<&Card, With<Selected>>) {
+pub(crate) fn check_set(_trigger: Trigger<Pointer<Click>>, query: Query<&Card, With<Selected>>) {
     let mut cards = query.iter();
     if cards.len() == 3 {
         let (a, b, c) = (
@@ -41,7 +41,7 @@ pub(crate) fn check_set(trigger: Trigger<Pointer<Click>>, query: Query<&Card, Wi
             cards.next().unwrap(),
             cards.next().unwrap(),
         );
-        _is_set((a, b, c));
+        info!("Is set: {}", is_set((a, b, c)));
     } else if cards.len() > 3 {
         info!("Too many cards!")
     } else if cards.len() < 3 {
@@ -49,6 +49,22 @@ pub(crate) fn check_set(trigger: Trigger<Pointer<Click>>, query: Query<&Card, Wi
     }
 }
 
-fn _is_set((_a, _b, _c): (&Card, &Card, &Card)) -> bool {
-    todo!()
+fn is_set((a, b, c): (&Card, &Card, &Card)) -> bool {
+    let color = {
+        ((a.color == b.color) && (b.color == c.color) && (c.color == a.color))
+            || ((a.color != b.color) && (b.color != c.color) && (c.color != a.color))
+    };
+    let number = {
+        ((a.number == b.number) && (b.number == c.number) && (c.number == a.number))
+            || ((a.number != b.number) && (b.number != c.number) && (c.number != a.number))
+    };
+    let pattern = {
+        ((a.pattern == b.pattern) && (b.pattern == c.pattern) && (c.pattern == a.pattern))
+            || ((a.pattern != b.pattern) && (b.pattern != c.pattern) && (c.pattern != a.pattern))
+    };
+    let shape = {
+        ((a.shape == b.shape) && (b.shape == c.shape) && (c.shape == a.shape))
+            || ((a.shape != b.shape) && (b.shape != c.shape) && (c.shape != a.shape))
+    };
+    color && number && pattern && shape
 }