diff --git a/main.lua b/main.lua
index 4c8f967..81cf09f 100644
--- a/main.lua
+++ b/main.lua
@@ -1,3 +1,5 @@
+poke(0x5F2D, 3)
+
 --
 -- constants
 --
@@ -91,21 +93,49 @@ end
 local Board = {}
 function Board.new()
 	local width = 10
-	local t = [[
-		2,0,2,0,0,2,1,0,1,2,
-		0,0,0,0,0,0,0,0,0,1,
-		0,1,0,0,0,0,0,0,0,0,
-		0,2,0,0,0,0,0,1,0,2,
-		0,0,1,0,0,2,0,1,0,1,
-		0,0,0,0,1,1,0,0,0,0,
-		0,2,2,0,0,0,0,0,0,2,
-		0,0,0,0,2,0,0,0,0,0,
-		0,0,2,0,0,1,0,0,0,0,
-		0,2,0,0,2,0,2,0,0,0
+	-- local t = [[
+	-- 	2,0,2,0,0,2,1,0,1,2,
+	-- 	0,0,0,0,0,0,0,0,0,1,
+	-- 	0,1,0,0,0,0,0,0,0,0,
+	-- 	0,2,0,0,0,0,0,1,0,2,
+	-- 	0,0,1,0,0,2,0,1,0,1,
+	-- 	0,0,0,0,1,1,0,0,0,0,
+	-- 	0,2,2,0,0,0,0,0,0,2,
+	-- 	0,0,0,0,2,0,0,0,0,0,
+	-- 	0,0,2,0,0,1,0,0,0,0,
+	-- 	0,2,0,0,2,0,2,0,0,0
+	-- ]]
+		local t = [[
+		0,0,0,0,0,0,0,0,0,0,
+		0,0,0,0,0,0,0,0,0,0,
+		0,0,0,0,0,0,0,0,0,0,
+		0,0,0,0,0,0,0,0,0,0,
+		0,0,0,0,0,0,0,0,0,0,
+		0,0,0,0,0,0,0,0,0,0,
+		0,0,0,0,0,0,0,0,0,0,
+		0,0,0,0,0,0,0,0,0,0,
+		0,0,0,0,0,0,0,0,0,0,
+		0,0,0,0,0,0,0,0,0,0
 	]]
 	local tiles = split(t)
 
 	return {
+		reset = function(self)
+			local t = [[
+				0,0,0,0,0,0,0,0,0,0,
+				0,0,0,0,0,0,0,0,0,0,
+				0,0,0,0,0,0,0,0,0,0,
+				0,0,0,0,0,0,0,0,0,0,
+				0,0,0,0,0,0,0,0,0,0,
+				0,0,0,0,0,0,0,0,0,0,
+				0,0,0,0,0,0,0,0,0,0,
+				0,0,0,0,0,0,0,0,0,0,
+				0,0,0,0,0,0,0,0,0,0,
+				0,0,0,0,0,0,0,0,0,0
+			]]
+			tiles = split(t)
+		end,
+
 		getTile = function(self, idx)
 			return tiles[idx]
 		end,
@@ -142,11 +172,101 @@ function Board.new()
 			return ret
 		end,
 
-		solve = function(self)
+		isComplete = function(self)
+			return count(tiles, 0) == 0
+		end,
+
+		isValid = function(self)
+			local rows = self:getRows()
+			for row in all(rows) do
+				-- check count
+				if count(row, BLUE) ~= count(row, YELLOW) then
+					printh("uneven count")
+					return false
+				end
+				-- check identical lines
+				for k,other in ipairs(rows) do
+					if equal(other, row) and other ~= row then
+						printh("equal rows "..k)
+						return false
+					end
+				end
+				-- check triples
+				if self:countConsecutives(row) > 2 then
+					printh("triples")
+					return false
+				end
+			end
+
+			local cols = self:getCols()
+			for col in all(cols) do
+				-- check count
+				if count(col, BLUE) ~= count(col, YELLOW) then
+					printh("uneven count")
+					return false
+				end
+				-- check identical lines
+				for other in all(cols) do
+					if equal(other, col) and other ~= col then
+					printh("equal cols")
+						return false
+					end
+				end
+				-- check triples
+				if self:countConsecutives(col) > 2 then
+					printh("triples")
+					return false
+				end
+			end
+			return true
+		end,
+
+		countConsecutives = function(self, line)
+			local count = 0
+			local last = 0
+			for v in all(line) do
+				if v ~= last then
+					last = 0
+				else
+					last = v
+					count += 1
+				end
+			end
+			return count
+		end,
+
+		-- Returns the index of a random zero
+		getRandomZero = function(self, v)
+			assert(count(tiles, 0) > 0, "No zero left")
+			local zeroes = filter(tiles, function(v) return v == 0 end, true)
+			local z = {}
+			for k,v in pairs(zeroes) do
+				add(z, k)
+			end
+			return rnd(z)
+		end,
+
+		tostring = function(self)
+			local str = ''
+			for v in all(tiles) do
+				str ..= ", " .. v
+			end
+			return str
+		end,
+
+		solve = function(self, random)
+			local old = self:tostring()
 			self:surroundDoubles()
 			self:splitTriples()
 			self:fillLines()
 			self:noIdenticalLines()
+			local changed = old ~= self:tostring()
+			if not changed and random and not self:isComplete() then
+				-- Set a random color
+				local z = self:getRandomZero()
+				self:fill(z, rnd({BLUE, YELLOW}))
+				printh("!!!!!!!!!!!!!!!!! RANDOM FILL AT " .. z)
+			end
 		end,
 
 		surroundDoubles = function(self)
@@ -321,7 +441,7 @@ function Board.new()
 		draw = function(self)
 			for k,v in ipairs(tiles) do
 				local x,y = self:idx_xy(k)
-				local color = v == BLUE and 12 or v == YELLOW and 10 or 1
+				local color = v == BLUE and 9 or v == YELLOW and 3 or 1
 				local w = 10
 				local p = 1
 				rectfill((x-1)*w + (x-1)*(p+1), (y-1)*w + (y-1)*(p+1), w, w, color)
@@ -340,15 +460,21 @@ local board = Board.new()
 function _init()
 end
 
-function _update()
+function _update60()
+	board:solve(true)
+	-- if time() % .01 == 0 then
+	-- end
+	if board:isComplete() then
+		if not board:isValid() then
+			printh("NOT VALID")
+			board:reset()
+		end
+	end
 end
 
 function _draw()
 	cls()
-	if time() % .5 == 0 then
-		printh("==")
-		printh("==")
-		board:solve()
-	end
 	board:draw()
+	circfill(stat(32), stat(33), 0, 7)
+	circ(stat(32), stat(33), 1, 0)
 end