diff --git a/src/Hastron/Game/Engine.hs b/src/Hastron/Game/Engine.hs
new file mode 100644
index 0000000..83942d0
--- /dev/null
+++ b/src/Hastron/Game/Engine.hs
@@ -0,0 +1,8 @@
+module Hastron.Game.Engine where
+
+import Hastron.Game.Types
+
+type GameStep = Game -> InEvent -> (Game, [OutEvent])
+
+stepGame :: GameStep
+stepGame game inEvent = undefined
diff --git a/src/Hastron/Game/Types.hs b/src/Hastron/Game/Types.hs
new file mode 100644
index 0000000..2bbde81
--- /dev/null
+++ b/src/Hastron/Game/Types.hs
@@ -0,0 +1,57 @@
+module Hastron.Game.Types where
+
+import Data.HashMap.Strict (HashMap)
+
+type Point = (Int, Int)
+
+data Direction = Left | Right | Up | Down deriving (Show, Eq, Ord, Enum)
+
+data Velocity = Velocity Double Direction deriving (Show, Eq, Ord)
+
+type PlayerId = Int
+
+data PlayerState = PlayerAlive
+                 | PlayerDead
+                 | PlayerDisconnected
+                 | PlayerLeft
+                 deriving (Show, Eq, Ord, Enum)
+
+type PlayerTrail = [Point]
+
+data PlayerBoost = PlayerBoost { boostActive :: Bool
+                               , boostFuel   :: Double
+                               } deriving (Show, Eq)
+
+type PlayerScore = Int
+
+data Player = Player { playerId       :: PlayerId
+                     , playerState    :: PlayerState
+                     , playerPosition :: Point
+                     , playerVelocity :: Velocity
+                     , playerTrail    :: PlayerTrail
+                     , playerBoost    :: PlayerBoost
+                     , playerScore    :: PlayerScore
+                     } deriving (Show, Eq)
+
+data PlayerEndState = PlayerWinner | PlayerLoser | PlayerDropped
+                      deriving (Show, Eq, Ord, Enum)
+
+data GameState = GameStarted | GameInit | GameFinished
+                 deriving (Show, Eq, Ord, Enum)
+
+data Game = Game { gamePlayers :: [Player]
+                 , gameState   :: GameState
+                 } deriving (Show, Eq)
+
+data InEvent = InPlayerTurnLeft PlayerId
+             | InPlayerTurnRight PlayerId
+             | InPlayerBoostActivate PlayerId
+             | InPlayerBoostDeactivate PlayerId
+             | InPlayerStateChange PlayerId PlayerState
+             deriving (Show, Eq, Ord)
+
+data OutEvent = OutPlayerPosition PlayerId Point Direction
+              | OutPlayerStateChange PlayerId PlayerState Point
+              | OutGameStateChange GameState
+              | OutGameOver (HashMap PlayerId (PlayerScore, PlayerEndState))
+              deriving (Show, Eq)
diff --git a/src/Hastron/Server/Types.hs b/src/Hastron/Server/Types.hs
index caeca8f..7c60b7d 100644
--- a/src/Hastron/Server/Types.hs
+++ b/src/Hastron/Server/Types.hs
@@ -7,42 +7,12 @@ import           Data.HashMap.Strict (HashMap)
 import qualified Data.Text           as T
 import           GHC.Generics
 
-
-type Point = (Int, Int)
-
-type Velocity = (Double, Double)
+import Hastron.Game.Types
 
 data User = User { userName :: T.Text
                  } deriving (Show, Eq, Ord, Generic)
 instance Hashable User
 
-data PlayerState = PlayerAlive | PlayerDead | PlayerDisconnected
-                   deriving (Show, Eq, Ord, Enum)
-
-type PlayerTrail = [Point]
-
-data PlayerBoost = PlayerBoost { boostActive :: Bool
-                               , boostFuel   :: Double
-                               } deriving (Show, Eq)
-
-type PlayerScore = Int
-
-data Player = Player { playerUser     :: User
-                     , playerState    :: PlayerState
-                     , playerPosition :: Point
-                     , playerVelocity :: Velocity
-                     , playerTrail    :: PlayerTrail
-                     , playerBoost    :: PlayerBoost
-                     , playerScore    :: PlayerScore
-                     } deriving (Show, Eq)
-
-data GameState = GameStarted | GamePaused | GameStarting | GameFinished
-                 deriving (Show, Eq, Ord, Enum)
-
-data Game = Game { gamePlayers :: [Player]
-                 , gameState   :: GameState
-                 } deriving (Show, Eq)
-
 data RoomUserState = RoomUserJoined | RoomUserReady | RoomUserPlaying
                      deriving (Show, Eq)