diff --git a/board.lua b/board.lua
index 622d63d..4ceffb4 100644
--- a/board.lua
+++ b/board.lua
@@ -4,6 +4,7 @@ function board:init(ruleset)
  self.ruleset=ruleset
  self.cursor=cursor:new(self)
  self.animator=animator:new()
+ self.checkpoint=nil
  self.slots={}
  self.wells={}
 
@@ -67,12 +68,20 @@ function board:deal(seed)
  end
 end
 
+function board:undo()
+ if (self.checkpoint) self.checkpoint:apply(self) print("applied")
+ self.checkpoint=nil
+end
+
 function board:on_idle()
  self:find_automove()
 end
 
+function board:pre_move(card)
+ self.checkpoint=checkpoint:new(self,card)
+end
+
 function board:on_move()
- -- TODO: Make checkpoint
  self:find_automove()
 end
 
@@ -142,6 +151,13 @@ function board:draw()
   end
  end)
 
+ if self.checkpoint then
+  local cpl=self.ruleset.layouts:checkpoint()
+  local x,y=cpl:place_card(0)
+  self.ruleset.deck:draw_card(x,y,self.checkpoint.card,{shadowed=true})
+  print("❎",x+1,y+9,7)
+ end
+
  self.animator:draw()
 
  if self.animator:idle() then
diff --git a/checkpoint.lua b/checkpoint.lua
new file mode 100644
index 0000000..8b654d5
--- /dev/null
+++ b/checkpoint.lua
@@ -0,0 +1,39 @@
+checkpoint=klass()
+function checkpoint:init(board,card)
+ self.card=card
+ self.slots={}
+ self.wells={}
+ for s=1,#board.slots do
+  local cnt={}
+  for c in all(board.slots[s].contents) do
+   add(cnt,c)
+  end
+  self.slots[s]=cnt
+ end
+ for w=1,#board.wells do
+  local cnt={}
+  for c in all(board.wells[w].contents) do
+   add(cnt,c)
+  end
+  self.wells[w]=cnt
+ end
+end
+
+function checkpoint:apply(board)
+ for s=1,#board.slots do
+  while #board.slots[s].contents>0 do
+   deli(board.slots[s].contents)
+  end
+  for i in all(self.slots[s]) do
+   add(board.slots[s].contents,i)
+  end
+ end
+ for w=1,#board.wells do
+  while #board.wells[w].contents>0 do
+   deli(board.wells[w].contents)
+  end
+  for i in all(self.wells[w]) do
+   add(board.wells[w].contents,i)
+  end
+ end
+end
\ No newline at end of file
diff --git a/cursor.lua b/cursor.lua
index a54ebaf..d624445 100644
--- a/cursor.lua
+++ b/cursor.lua
@@ -37,6 +37,7 @@ function cursor:toggle_grab()
  if acc==acceptance_state.not_grabbed then
   if (self.board.slots[self:hover_slot()]:peek()) self.grabbed=self:hover_slot()
  elseif acc==acceptance_state.would_accept then
+  self.board:pre_move(src:peek())
   local card=src:pop()
   tar:add(card)
   self.grabbed=nil
diff --git a/main.lua b/main.lua
index 222fe08..fcd5a66 100644
--- a/main.lua
+++ b/main.lua
@@ -14,6 +14,7 @@ function main:update()
   if (btnp(2)) self.board.cursor:move_y(-1)
   if (btnp(3)) self.board.cursor:move_y(1)
   if (btnp(4)) self.board.cursor:toggle_grab()
+  if (btnp(5)) self.board:undo()
  end
 end
 
diff --git a/main.p8 b/main.p8
index 80ebc48..d67180c 100644
--- a/main.p8
+++ b/main.p8
@@ -5,6 +5,7 @@ __lua__
 #include animator.lua
 #include board.lua
 #include board_animations.lua
+#include checkpoint.lua
 #include dealer.lua
 #include cursor.lua
 #include layout.lua
diff --git a/progression.lua b/progression.lua
index d19a976..c428912 100644
--- a/progression.lua
+++ b/progression.lua
@@ -1,5 +1,5 @@
 progression={
- ruleset:new(11,5,10,25),
+ ruleset:new(11,4,13,22,"ff"),
  -- level 1
  ruleset:new(5,1,9,0), -- by test: always winnable
  -- level 2
diff --git a/ruleset.lua b/ruleset.lua
index c783131..c4505a2 100644
--- a/ruleset.lua
+++ b/ruleset.lua
@@ -176,6 +176,11 @@ function ruleset:generate_layouts()
   assert(false,"unknown well")
  end
 
+ function layouts:checkpoint()
+   local wx=(ruleset.n_slots\2)*10
+   return layout:new(x+wx,1,layout_mode.obscured)
+ end
+
  function layouts:slot(i)
   if i<=ruleset.n_slots then
    local sx=(i-1)*10
diff --git a/simulator/level_7.txt b/simulator/level_7.txt
index 14968d1..5dd58a2 100644
--- a/simulator/level_7.txt
+++ b/simulator/level_7.txt
@@ -852,3 +852,200 @@
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