diff --git a/docs/LICENSE b/LICENSE
similarity index 100%
rename from docs/LICENSE
rename to LICENSE
diff --git a/backend/old_tests/api/effects_test.clj b/backend/old_tests/api/effects_test.clj
deleted file mode 100644
index a125d40..0000000
--- a/backend/old_tests/api/effects_test.clj
+++ /dev/null
@@ -1,23 +0,0 @@
-(ns api.effects-test
-  (:require [expectations.clojure.test :refer :all]
-            [clojure.test :as ctest]
-            [mocking :as mocking]
-            [api.base :as api]))
-
-(ctest/use-fixtures :each mocking/mock-persistence)
-
-(defexpect playing-effects
-  ; Can play cards with effects and they act as expected
-  (expect
-    -100
-    (let [game (api/create-game {:hands [[{:power 0} {:power 100}]
-                                         [{:power 1} {:power 10 :add-power -100}]]})
-          game-id (:game-id game)
-          player-id (:player-id game)
-          opponent-id (:player-id (api/add-player game-id))]
-      (api/play-card-as-player game-id player-id   0 0)
-      (api/play-card-as-player game-id opponent-id 0 1)
-      (api/play-card-as-player game-id player-id   0 1)
-      (api/play-card-as-player game-id opponent-id 0 1 [:rows 0 :cards 0])
-      (get-in (api/get-game game-id player-id)
-              [:rows 0 :cards 0 :power]))))
diff --git a/backend/old_tests/api/messages_test.clj b/backend/old_tests/api/messages_test.clj
deleted file mode 100644
index 89df6b4..0000000
--- a/backend/old_tests/api/messages_test.clj
+++ /dev/null
@@ -1,71 +0,0 @@
-(ns api.messages-test
-  (:require [expectations.clojure.test :refer :all]
-            [clojure.test :as ctest]
-            [mocking :as mocking]
-            [api.base :as api]
-            [configs.messages :as messages]))
-
-(ctest/use-fixtures :each mocking/mock-persistence)
-
-(defexpect no-opp-on-creation
-  (let [game (api/create-game)]
-    (expect
-      messages/no-opp
-      (:status game))
-    (expect
-      messages/no-opp
-      (:status
-        (api/get-game (:game-id game) (:player-id game))))))
-
-(defexpect play-on-both-players
-  (expect
-    messages/play
-    (-> (api/create-game)
-        :game-id
-        (api/add-player)
-        :status)))
-
-(defexpect wait-on-card-played
-  (expect
-    messages/wait
-    (let [game (api/create-game)
-          game-id (:game-id game)
-          player-id (:player-id game)]
-      (do (api/add-player game-id)
-          (:status
-            (api/play-card-as-player game-id player-id 0 0))))))
-
-(defexpect play-on-not-played
-  (let [game (api/create-game)
-        game-id (:game-id game)
-        player-id (:player-id game)
-        opponent-id (:player-id (api/add-player game-id))]
-    (expect
-      messages/play
-      (do (api/play-card-as-player game-id player-id 0 0)
-          (:status
-            (api/play-card-as-player game-id opponent-id 0 0))))
-
-    (expect
-      messages/play
-      (do (api/play-card-as-player game-id opponent-id 0 0)
-          (:status
-            (api/get-game game-id player-id))))))
-
-(defexpect out-of-turn
-  ; Game gives error when playing and shouldn't
-  (let [game (api/create-game)
-        game-id (:game-id game)
-        player-id (:player-id game)]
-
-    (expect
-      {:error messages/out-of-turn}
-      (api/play-card-as-player game-id player-id 0 0))
-
-    (expect
-      {:error messages/out-of-turn}
-      (do (api/add-player game-id)
-          (api/play-card-as-player game-id player-id 0 0)
-          (api/play-card-as-player game-id player-id 0 0)))))
-
-
diff --git a/backend/old_tests/api/play_test.clj b/backend/old_tests/api/play_test.clj
deleted file mode 100644
index f66919f..0000000
--- a/backend/old_tests/api/play_test.clj
+++ /dev/null
@@ -1,41 +0,0 @@
-(ns api.play-test
-  (:require [expectations.clojure.test :refer :all]
-            [clojure.test :as ctest]
-            [mocking :as mocking]
-            [api.base :as api]
-            [configs.hands :as hands]))
-
-(ctest/use-fixtures :each mocking/mock-persistence)
-
-(defexpect playing-cards
-  (let [game (api/create-game)
-        game-id (:game-id game)
-        player-id (:player-id game)
-        opponent (api/add-player game-id)
-        opponent-id (:player-id opponent)]
-    ; Cards in hand have power
-    (expect
-      #(empty? (filter (fn [e] (nil? (:power e))) %))
-      (:hand game))
-
-    ; Card is not removed if opponent has not yet played
-    (expect
-      #(= (count (:hand %)) (count hands/default-hand))
-      (do
-        (api/play-card-as-player game-id player-id 0 0)
-        (api/get-game game-id player-id)))
-
-    ; Cards are removed from hands upon both having played
-    (expect
-      #(= (count (:hand %)) (dec (count hands/default-hand)))
-      (api/play-card-as-player game-id opponent-id 0 1))
-
-    ; card played is owned by self
-    (expect
-      #(= :me (get-in % [:rows 0 :cards 0 :owner]))
-      (api/get-game game-id player-id))
-
-    ; opponent's card is owned by him
-    (expect
-      #(= :opponent (get-in % [:rows 1 :cards 0 :owner]))
-      (api/get-game game-id player-id))))
diff --git a/backend/old_tests/api/scores_test.clj b/backend/old_tests/api/scores_test.clj
deleted file mode 100644
index 10aaa4a..0000000
--- a/backend/old_tests/api/scores_test.clj
+++ /dev/null
@@ -1,59 +0,0 @@
-(ns api.scores-test
-  (:require [expectations.clojure.test :refer :all]
-            [clojure.test :as ctest]
-            [mocking :as mocking]
-            [api.base :as api]
-            [test-hand :as hand]
-            [autoplay :as autoplay]
-            [configs.hands :as hands]))
-
-(ctest/use-fixtures :each mocking/mock-persistence)
-
-(defexpect rows-won
-  (expect
-    #(= [3 1] 
-        (:scores %))
-    (autoplay/as-api
-      (fn [i] (mod i 4))
-      (fn [i] 0)))
-
-  (defexpect rows-tied
-    (expect
-      #(= [2 2]
-          (:scores %))
-      (autoplay/as-api
-        (fn [i] (mod i 2))
-        (fn [i] (+ (mod i 2) 2))))))
-
-(defexpect power-in-rows
-  (let [game-state (api/create-game)
-        game-id (:game-id game-state)
-        player-id (:player-id game-state)
-        opponent-id (:player-id (api/add-player game-id))]
-
-    ; Game begins with scores at 0
-    (expect
-      [[0 0] [0 0] [0 0] [0 0] [0 0]]
-      (:rows-power (api/get-game game-id player-id)))
-
-    ; Play on same row
-    (expect
-      [[(hand/power-of-nth 0) (hand/power-of-nth 1)]
-       [0 0] [0 0] [0 0] [0 0]]
-      (do
-        (api/play-card-as-player game-id player-id 0 0)
-        (api/play-card-as-player game-id opponent-id 1 0)
-        (:rows-power (api/get-game game-id player-id))))
-
-    ; Play on different rows
-    (expect
-      [[
-        (+ (hand/power-of-nth 0) (hand/power-of-nth 1))
-        (hand/power-of-nth 0)]
-       [0 0]
-       [0 (hand/power-of-nth 1)]
-       [0 0] [0 0]]
-      (do
-        (api/play-card-as-player game-id player-id 0 2)
-        (api/play-card-as-player game-id opponent-id 0 0)
-        (:rows-power (api/get-game game-id opponent-id))))))
diff --git a/backend/old_tests/api/winner_test.clj b/backend/old_tests/api/winner_test.clj
deleted file mode 100644
index 2a64904..0000000
--- a/backend/old_tests/api/winner_test.clj
+++ /dev/null
@@ -1,31 +0,0 @@
-(ns api.winner-test
-  (:require [expectations.clojure.test :refer :all]
-            [clojure.test :as ctest]
-            [mocking :as mocking]
-            [autoplay :as autoplay]))
-
-(ctest/use-fixtures :each mocking/mock-persistence)
-
-(defexpect tie
-  ; Both stack all cards on one row -> tie
-  (expect
-    #(= :tie (:winner %))
-    (autoplay/as-api
-      (fn [i] 0)
-      (fn [i] 0))))
-
-(defexpect i-win
-  ; Opponent stacks all cards on one row and I spread -> I win
-  (expect
-    #(= :me (:winner %))
-    (autoplay/as-api
-      (fn [i] (mod i 4))
-      (fn [i] 0))))
-
-(defexpect i-lose
-  ; I stack all cards on one row and opponent spreads -> Opponent wins
-  (expect
-    #(= :opponent (:winner %))
-    (autoplay/as-api
-      (fn [i] 0)
-      (fn [i] (mod i 4)))))
diff --git a/backend/old_tests/autoplay.clj b/backend/old_tests/autoplay.clj
deleted file mode 100644
index 5f32a90..0000000
--- a/backend/old_tests/autoplay.clj
+++ /dev/null
@@ -1,23 +0,0 @@
-(ns autoplay
-  (:require [configs.hands :as hands]
-            [configs.rows :as rows]
-            [api.base :as api]
-            [rules.create-game :as create-game]
-            [rules.play-card :as play-card]))
-
-(defn as-api
-  [strategy1 strategy2]
-  (let [game (api/create-game {:hand hands/simple-hand
-                               :limits rows/limitless})
-        game-id (:game-id game)
-        player-id (:player-id game)
-        opponent-id (:player-id (api/add-player game-id))]
-    (loop [game-state game
-           iteration (count (:hand game))]
-        (if (= 0 iteration)
-          (api/get-game game-id player-id)
-          (recur
-            (do
-              (api/play-card-as-player game-id player-id 0 (strategy1 iteration))
-              (api/play-card-as-player game-id opponent-id 0 (strategy2 iteration)))
-            (dec iteration))))))
diff --git a/backend/old_tests/test_hand.clj b/backend/old_tests/test_hand.clj
deleted file mode 100644
index 0847f05..0000000
--- a/backend/old_tests/test_hand.clj
+++ /dev/null
@@ -1,8 +0,0 @@
-(ns test-hand
-  (:require [configs.hands :as hands]))
-
-(defn power-of-nth
-  ([x]
-    (power-of-nth x hands/default-hand))
-  ([x hand]
-    (get-in hand [x :power])))
diff --git a/backend/src/api/base.clj b/backend/src/api/base.clj
index 464ee43..dee1e05 100644
--- a/backend/src/api/base.clj
+++ b/backend/src/api/base.clj
@@ -13,13 +13,21 @@
   (player-view/get-game-as-player (persistence/fetch-game game-id) player-id))
 
 (defn play-card-as-player
+  "Plays a card give and returns the game sate as seen by the player"
   [game-id player-id card-id row-id & target]
   (let [game-state (persistence/fetch-game game-id)]
+    (if (and (= game-id (:game-id game-state))
+          (or (= player-id (first (:player-ids game-state)))
+            (= player-id (second (:player-ids game-state)))))
       (if (= (:status (get-game game-id player-id)) messages/play)
-          (do
-            (persistence/save-game (play-card/play-card game-state player-id card-id row-id (first target)))
-            (get-game game-id player-id))
-          {:error messages/out-of-turn})))
+          (let [new-game-state (play-card/play-card game-state player-id card-id row-id (first target))]
+            (if (contains? new-game-state :error)
+              new-game-state
+              (do
+                (persistence/save-game new-game-state)
+                (get-game game-id player-id))))
+          {:error messages/out-of-turn})
+    {:error messages/invalid-id})))
 
 (defn ^:private create-empty-game
   "Creates a new instance of a game lobby"
diff --git a/backend/src/configs/messages.clj b/backend/src/configs/messages.clj
index 1f32a01..f7b11af 100644
--- a/backend/src/configs/messages.clj
+++ b/backend/src/configs/messages.clj
@@ -23,3 +23,5 @@
 (def no-row (get-in config-file [:messages :no-row]))
 
 (def lobby-not-created (get-in config-file [:messages :no-lobby-not-created]))
+
+(def invalid-id (get-in config-file [:messages :invalid-id]))
diff --git a/backend/test/api/base_test.clj b/backend/test/api/base_test.clj
index a2ce642..0745c2c 100644
--- a/backend/test/api/base_test.clj
+++ b/backend/test/api/base_test.clj
@@ -38,3 +38,37 @@
 (defexpect join-empty
   (expect {:error messages/lobby-not-created}
               (base/add-player 0)))
+
+(defexpect play-card-messages
+
+  (let [game (base/create-game)
+        game-id (:game-id game)
+        p1 (:player-id game)
+        p2 (:player-id (base/add-player game-id))]
+    
+    (expect {:error messages/invalid-id}
+            (base/play-card-as-player 9999999999 p1 0 0))
+    
+    (expect {:error messages/invalid-id}
+            (base/play-card-as-player game-id "MrInvalid" 0 0))
+    
+    (expect {:error messages/no-row}
+            (base/play-card-as-player game-id p1 1 99))
+            
+    (expect {:error messages/not-owned-card}
+            (base/play-card-as-player game-id p1 15 0))
+    
+    (expect {:error messages/not-owned-card}
+            (base/play-card-as-player game-id p2 0 0))
+    
+    (expect messages/wait
+            (:status (base/play-card-as-player game-id p1 1 0)))
+
+    (expect {:error messages/out-of-turn}
+            (base/play-card-as-player game-id p1 1 0))
+
+    (expect messages/play
+            (:status (base/play-card-as-player game-id p2 11 2)))
+
+    (expect messages/wait
+            (:status (base/play-card-as-player game-id p2 11 1)))))
diff --git a/configs/config.yml b/configs/config.yml
index 5839213..8c9a42f 100644
--- a/configs/config.yml
+++ b/configs/config.yml
@@ -9,3 +9,4 @@ messages:
     need-target: "A target is needed"
     not-owned-card: "You don't own this card"
     no-row: "This row doesn't exist"
+    invalid-id: "Wrong id"