diff --git a/lib/viral_spiral/room/state/change.ex b/lib/viral_spiral/room/state/change.ex
index 4dba351..143c8c1 100644
--- a/lib/viral_spiral/room/state/change.ex
+++ b/lib/viral_spiral/room/state/change.ex
@@ -7,5 +7,5 @@ defprotocol ViralSpiral.Room.State.Change do
   - change_description: a Keyword List with parameters defining the change
   """
   @spec apply_change(t(), keyword()) :: t()
-  def apply_change(score, change_description)
+  def apply_change(state, change_description)
 end
diff --git a/lib/viral_spiral/room/state/deck.ex b/lib/viral_spiral/room/state/deck.ex
new file mode 100644
index 0000000..8bd9428
--- /dev/null
+++ b/lib/viral_spiral/room/state/deck.ex
@@ -0,0 +1,43 @@
+defmodule ViralSpiral.Room.State.Deck do
+  alias ViralSpiral.Room.State.Deck
+  alias ViralSpiral.Room.State.Change
+
+  defstruct available_cards: nil,
+            dealt_cards: nil
+
+  @type change_opts :: [type: :remove | :shuffle]
+  @type t :: %__MODULE__{
+          available_cards: MapSet.t(),
+          dealt_cards: MapSet.t()
+        }
+
+  @doc """
+  todo : datastructure of cards, optimized for game operations
+  """
+  def new(cards) do
+    %Deck{
+      available_cards: MapSet.new(cards),
+      dealt_cards: MapSet.new()
+    }
+  end
+
+  defimpl Change do
+    @doc """
+    Handle changes to the deck.
+
+    Possible changes :
+    - Make card unavailable for drawing. Implemted by change type :remove
+    - Shuffle card. Implemented by change type :shuffle
+    """
+    @spec apply_change(Deck.t(), Deck.change_opts()) :: Deck.t()
+    def apply_change(%Deck{} = deck, opts) do
+      case opts[:type] do
+        :remove ->
+          Map.put(deck, :available_cards, MapSet.difference(deck.available_cards, opts[:target]))
+
+        :shuffle ->
+          Map.put(deck, :availabe_cards, Enum.shuffle(deck))
+      end
+    end
+  end
+end
diff --git a/lib/viral_spiral/room/state/round.ex b/lib/viral_spiral/room/state/round.ex
index 3ae3b47..771278d 100644
--- a/lib/viral_spiral/room/state/round.ex
+++ b/lib/viral_spiral/room/state/round.ex
@@ -24,6 +24,8 @@ defmodule ViralSpiral.Room.State.Round do
   # Doubt
   should it use game to initialize or players?
   """
+  alias ViralSpiral.Room.State.Change
+  alias ViralSpiral.Game.Player
 
   # alias ViralSpiral.Game.Player
 
@@ -32,6 +34,8 @@ defmodule ViralSpiral.Room.State.Round do
             current: 0,
             skip: nil
 
+  @type change_opts :: [type: :next]
+
   @type t :: %__MODULE__{
           order: list(String.t()),
           count: integer(),
@@ -42,7 +46,8 @@ defmodule ViralSpiral.Room.State.Round do
   @doc """
   todo : this doesn't really need the players, merely a count of players, maybe?
   """
-  def new(player_list) do
+  @spec new(list(Player.t())) :: ViralSpiral.Room.State.Round.t()
+  def new(player_list) when is_list(player_list) do
     order =
       Enum.shuffle(player_list)
       |> Enum.map(& &1.id)
@@ -108,4 +113,15 @@ defmodule ViralSpiral.Room.State.Round do
 
     Map.merge(round, changes)
   end
+
+  defimpl Change do
+    alias ViralSpiral.Room.State.Round
+
+    @spec apply_change(Round.t(), Round.change_opts()) :: Round.t()
+    def apply_change(state, opts) do
+      case opts[:type] do
+        :next -> Round.next(state)
+      end
+    end
+  end
 end
diff --git a/lib/viral_spiral/room/state/turn.ex b/lib/viral_spiral/room/state/turn.ex
index 3b6b960..146e34f 100644
--- a/lib/viral_spiral/room/state/turn.ex
+++ b/lib/viral_spiral/room/state/turn.ex
@@ -7,6 +7,7 @@ defmodule ViralSpiral.Room.State.Turn do
 
   todo : could the field be actions and not tied to every concrete thing like pass, discard etc.
   """
+  alias ViralSpiral.Room.State.Change
   alias ViralSpiral.Room.State.Turn
   alias ViralSpiral.Room.State.Round
 
@@ -61,6 +62,11 @@ defmodule ViralSpiral.Room.State.Turn do
     )
   end
 
-  def change(%Turn{} = _turn) do
+  defimpl Change do
+    def apply_change(turn, opts) do
+      case opts[:type] do
+        :next -> Turn.next(turn, opts[:target])
+      end
+    end
   end
 end
diff --git a/test/support/fixtures.ex b/test/support/fixtures.ex
index 464a637..b17b842 100644
--- a/test/support/fixtures.ex
+++ b/test/support/fixtures.ex
@@ -51,4 +51,15 @@ defmodule Fixtures do
   def card_affinity() do
     Card.new(:affinity)
   end
+
+  def player_list() do
+    room_config = %RoomConfig{}
+
+    [
+      Player.new(room_config) |> Player.set_name("adhiraj"),
+      Player.new(room_config) |> Player.set_name("aman"),
+      Player.new(room_config) |> Player.set_name("krys"),
+      Player.new(room_config) |> Player.set_name("farah")
+    ]
+  end
 end
diff --git a/test/viral_spiral/gameplay_test.exs b/test/viral_spiral/gameplay_test.exs
index 7aad115..7a367b4 100644
--- a/test/viral_spiral/gameplay_test.exs
+++ b/test/viral_spiral/gameplay_test.exs
@@ -18,11 +18,11 @@ defmodule ViralSpiral.GameTest do
       card = Fixtures.card_affinity()
 
       current_player = players[turn.current]
-      target_player = players[2]
+      target_player = players[Enum.at(turn.pass_to, 2)]
 
       Game.pass_card(game_state, card, current_player, target_player)
 
-      IO.inspect(game_state)
+      # IO.inspect(game_state)
       # IO.inspect(card)
     end
   end
diff --git a/test/viral_spiral/room/score/player_text.exs b/test/viral_spiral/room/state/player_text.exs
similarity index 100%
rename from test/viral_spiral/room/score/player_text.exs
rename to test/viral_spiral/room/state/player_text.exs
diff --git a/test/viral_spiral/room/score/room_test.exs b/test/viral_spiral/room/state/room_test.exs
similarity index 100%
rename from test/viral_spiral/room/score/room_test.exs
rename to test/viral_spiral/room/state/room_test.exs
diff --git a/test/viral_spiral/room/score/round_test.exs b/test/viral_spiral/room/state/round_test.exs
similarity index 86%
rename from test/viral_spiral/room/score/round_test.exs
rename to test/viral_spiral/room/state/round_test.exs
index baa4e71..67bdb33 100644
--- a/test/viral_spiral/room/score/round_test.exs
+++ b/test/viral_spiral/room/state/round_test.exs
@@ -1,4 +1,5 @@
 defmodule ViralSpiral.Room.State.RoundTest do
+  alias ViralSpiral.Room.State.Change
   alias ViralSpiral.Room.State.Round
   use ExUnit.Case
 
@@ -72,5 +73,15 @@ defmodule ViralSpiral.Room.State.RoundTest do
   end
 
   describe "changes" do
+    setup do
+      player_list = Fixtures.player_list()
+      round = Round.new(player_list)
+      %{round: round}
+    end
+
+    test "move to next round", %{round: round} do
+      new_round = Change.apply_change(round, type: :next)
+      assert new_round.current == 1
+    end
   end
 end
diff --git a/test/viral_spiral/room/score/turn_test.exs b/test/viral_spiral/room/state/turn_test.exs
similarity index 72%
rename from test/viral_spiral/room/score/turn_test.exs
rename to test/viral_spiral/room/state/turn_test.exs
index 8923ffc..61ae82a 100644
--- a/test/viral_spiral/room/score/turn_test.exs
+++ b/test/viral_spiral/room/state/turn_test.exs
@@ -1,4 +1,5 @@
 defmodule ViralSpiral.Room.State.TurnTest do
+  alias ViralSpiral.Room.State.Change
   alias ViralSpiral.Room.State.Turn
   alias ViralSpiral.Room.State.Round
   use ExUnit.Case
@@ -41,5 +42,19 @@ defmodule ViralSpiral.Room.State.TurnTest do
   end
 
   describe "changes" do
+    setup do
+      players = Fixtures.player_list()
+      round = Round.new(players)
+      turn = Turn.new(round)
+
+      current_player = Enum.at(round.order, 0)
+      to_pass_player = Enum.at(round.order, 2)
+      %{turn: turn, target: to_pass_player}
+    end
+
+    test "move to next turn", %{turn: turn, target: target} do
+      new_turn = Change.apply_change(turn, type: :next, target: target)
+      assert new_turn.current == target
+    end
   end
 end