diff --git a/game.lua b/game.lua
index 0b3c0ff..0647e62 100644
--- a/game.lua
+++ b/game.lua
@@ -68,6 +68,16 @@ function Game:step(ox,oy)
     if self.level_data[self.floor].walls[ty][tx]==1 then
         if self.player_item == "pickaxe" then
             --push to undo memory
+            self.undo_history[#self.undo_history+1] = {
+                "dig",
+                {
+                    floor = self.floor,
+                    px = self.player_x,
+                    py = self.player_y,
+                    wx = tx, 
+                    wy = ty,
+                }
+            }
             --remove wall
             self.level_data[self.floor].walls[ty][tx]=0
             --remove item
@@ -84,7 +94,16 @@ function Game:step(ox,oy)
                 break
             elseif entities[i].type == "enemy" then
                 if self.player_item == "vorpal" then
-                    --push to undo memory
+                    self.undo_history[#self.undo_history+1] = {
+                        "vorpal",
+                        {
+                            floor = self.floor,
+                            px = self.player_x,
+                            py = self.player_y,
+                            ent_type = entities[i].type, 
+                            ent = entities[i],
+                        }
+                    }
                     --remove entity
                     entities[i].type = nil
                     --remove item
@@ -94,6 +113,17 @@ function Game:step(ox,oy)
                     return
                 else
                     --push to undo memory
+                    self.undo_history[#self.undo_history+1] = {
+                        "fight",
+                        {
+                            floor = self.floor,
+                            px = self.player_x,
+                            py = self.player_y,
+                            power = self.player_power,
+                            ent_type = entities[i].type, 
+                            ent = entities[i],
+                        }
+                    }
                     --remove entity
                     entities[i].type = nil
                     --absorb power
@@ -103,6 +133,16 @@ function Game:step(ox,oy)
             elseif entities[i].type == "enemy_neg" then
                 if self.player_item == "vorpal" then
                     --push to undo memory
+                    self.undo_history[#self.undo_history+1] = {
+                        "vorpal",
+                        {
+                            floor = self.floor,
+                            px = self.player_x,
+                            py = self.player_y,
+                            ent_type = entities[i].type, 
+                            ent = entities[i],
+                        }
+                    }
                     --remove entity
                     entities[i].type = nil
                     --remove item
@@ -112,6 +152,17 @@ function Game:step(ox,oy)
                     return
                 else
                     --push to undo memory
+                    self.undo_history[#self.undo_history+1] = {
+                        "fight",
+                        {
+                            floor = self.floor,
+                            px = self.player_x,
+                            py = self.player_y,
+                            power = self.player_power,
+                            ent_type = entities[i].type, 
+                            ent = entities[i],
+                        }
+                    }
                     --remove entity
                     entities[i].type = nil
                     --absorb power
@@ -120,6 +171,17 @@ function Game:step(ox,oy)
                 end
             elseif entities[i].type == "elixir" then
                 --push to undo memory
+                    self.undo_history[#self.undo_history+1] = {
+                        "fight",
+                        {
+                            floor = self.floor,
+                            px = self.player_x,
+                            py = self.player_y,
+                            power = self.player_power,
+                            ent_type = entities[i].type, 
+                            ent = entities[i],
+                        }
+                    }
                 --remove entity
                 entities[i].type = nil
                 --double power
@@ -127,6 +189,17 @@ function Game:step(ox,oy)
                 break
             elseif entities[i].type == "gate" then
                 --push to undo memory
+                    self.undo_history[#self.undo_history+1] = {
+                        "fight",
+                        {
+                            floor = self.floor,
+                            px = self.player_x,
+                            py = self.player_y,
+                            power = self.player_power,
+                            ent_type = entities[i].type, 
+                            ent = entities[i],
+                        }
+                    }
                 --remove entity
                 entities[i].type = nil
                 --divide power by two
@@ -138,6 +211,16 @@ function Game:step(ox,oy)
                     return
                 end
                 --push to undo memory
+                self.undo_history[#self.undo_history+1] = {
+                    "item_get",
+                    {
+                        floor = self.floor,
+                        px = self.player_x,
+                        py = self.player_y,
+                        ent_type = entities[i].type, 
+                        ent = entities[i],
+                    }
+                }
                 --remove entity
                 entities[i].type = nil
                 --equip item
@@ -149,6 +232,16 @@ function Game:step(ox,oy)
                     return
                 end
                 --push to undo memory
+                self.undo_history[#self.undo_history+1] = {
+                    "item_get",
+                    {
+                        floor = self.floor,
+                        px = self.player_x,
+                        py = self.player_y,
+                        ent_type = entities[i].type, 
+                        ent = entities[i],
+                    }
+                }
                 --remove entity
                 entities[i].type = nil
                 --equip item
@@ -178,7 +271,38 @@ function Game:undo()
     if #self.undo_history == 0 then
         return
     end
-    
+
+    undo_item = self.undo_history[#self.undo_history]
+    if undo_item[1] == "vorpal" then
+        self.floor = undo_item[2].floor
+        self.player_x = undo_item[2].px
+        self.player_y = undo_item[2].py
+        undo_item[2].ent.type = undo_item[2].ent_type
+        self.player_item = "vorpal"
+    elseif undo_item[1] == "dig" then
+        self.floor = undo_item[2].floor
+        self.player_x = undo_item[2].px
+        self.player_y = undo_item[2].py
+        self.level_data[self.floor].walls[undo_item[2].wy][undo_item[2].wx]=1
+        self.player_item = "pickaxe"
+    elseif undo_item[1] == "item_get" then
+        self.floor = undo_item[2].floor
+        self.player_x = undo_item[2].px
+        self.player_y = undo_item[2].py
+        undo_item[2].ent.type = undo_item[2].ent_type
+        self.player_item = nil
+    elseif undo_item[1] == "fight" then
+        --works for elixirs and gates too
+        self.floor = undo_item[2].floor
+        self.player_x = undo_item[2].px
+        self.player_y = undo_item[2].py
+        self.player_power = undo_item[2].power
+        undo_item[2].ent.type = undo_item[2].ent_type
+    else
+        assert(false)
+    end
+    --remove the item from stack
+    self.undo_history[#self.undo_history] = nil
 end
 
 function Game:update(dt)