I'm not 100% sure...
sparkly(x,y) is recording which atoms are getting checked and then im lost :( how is it different from checked(x,y)?

atom>peg fix -- you're right, it works much better now :)
[code]
Graphics 640,400,0,2
Graphics 320,200,0,3
AppTitle "Atomino - Blitz"

background = CreateImage( 320,200)
SetBuffer ImageBuffer(background)
Color 192,192,192
Rect 63,15,194,170,0
;background = LoadImage("background.bmp")
atom_sprites = LoadAnimImage("atoms.bmp",24,24,0,9)
electron_sprites = CreateImage(24,24,128)

For t# = 0 To 127
 x = 10.5 + 10.5 * Sin(t# * 2.8125)
 y = 10.5 + 10.5 * Cos(t# * 2.8125)
 SetBuffer ImageBuffer(electron_sprites,127-t#)
 DrawBlock atom_sprites,x,y,8
Next

SetBuffer BackBuffer()
Dim atom(7,8) ; which atom is where (1-4)
Dim peg(7,8) ; which sides are connected
Dim checked(7,8)

Global space = 24
Global PUP = 1, PLEFT = 2, PDOWN = 4, PRIGTH = 8
Global nextAtom = 1

Global TotallyClean ;**********************************************
Dim Sparkly(7,8)

While Not KeyHit(1)
mx = MouseX()
my = MouseY()

;Cls
;Color 192,192,192
;Rect 63,15,194,170,0
DrawBlock background,0,0
DrawImage atom_sprites,280,140,nextAtom-1
;DrawBlock atom_sprites,0,0,nextAtom-1


If mx>63 And mx<253 And my>15 And my<183 Then
 cx = (MX-64)/space
 cy = (MY-16)/space
 DrawBlock atom_sprites,64+Floor(cx)*space,16+Floor(cy)*space,nextAtom-1 ; draw current atom at mouse position (cursor)


If MouseHit(1) And atom(cx,cy)=0 Then 
 atom(cx,cy)=nextAtom ; or whatever atom number
 nextAtom = Rnd(1,2)


  a$=Bin$(peg(cx ,cy))
  total=0
  For temp = 1 To Len(a$)
   If Mid$(a$,temp,1)=1 Then total = total+1
  Next

 If cy>0 And atom(cx,cy) > total Then
  ; check UP
  a$=Bin$(peg(cx ,cy-1))
  total=0
  For temp = 1 To Len(a$)
   If Mid$(a$,temp,1)=1 Then total = total+1
  Next
  If total < atom(cx,cy-1)
   peg(cx,cy-1)=peg(cx,cy-1) Or PDOWN
   peg(cx,cy)=peg(cx,cy) Or PUP
  End If
 End If ; cy>0


  a$=Bin$(peg(cx ,cy))
  total=0
  For temp = 1 To Len(a$)
   If Mid$(a$,temp,1)=1 Then total = total+1
  Next

 If cx>0 And atom(cx,cy) > total Then
  ; check LEFT
  a$=Bin$(peg(cx-1 ,cy))
  total=0
  For temp = 1 To Len(a$)
   If Mid$(a$,temp,1)=1 Then total = total+1
  Next
  If total < atom(cx-1,cy)
   peg(cx-1,cy)=peg(cx-1,cy) Or PRIGTH
   peg(cx,cy)=peg(cx,cy) Or PLEFT
  End If
 End If ; cx>0


  a$=Bin$(peg(cx ,cy))
  total=0
  For temp = 1 To Len(a$)
   If Mid$(a$,temp,1)=1 Then total = total+1
  Next

 If cy<6 And atom(cx,cy) > total Then
  ; check DOWN
  a$=Bin$(peg(cx ,cy+1))
  total=0
  For temp = 1 To Len(a$)
   If Mid$(a$,temp,1)=1 Then total = total+1
  Next
  If total < atom(cx,cy+1)
   peg(cx,cy+1)=peg(cx,cy+1) Or PUP
   peg(cx,cy)=peg(cx,cy) Or PDOWN
  End If
 End If ; cy<6

  a$=Bin$(peg(cx ,cy))
  total=0
  For temp = 1 To Len(a$)
   If Mid$(a$,temp,1)=1 Then total = total+1
  Next

 If cx<7 And atom(cx,cy) > total Then
  ; check RIGHT
  a$=Bin$(peg(cx+1 ,cy))
  total=0
  For temp = 1 To Len(a$)
   If Mid$(a$,temp,1)=1 Then total = total+1
  Next
  If total < atom(cx+1,cy)
   peg(cx+1,cy)=peg(cx+1,cy) Or PLEFT
   peg(cx,cy)=peg(cx,cy) Or PRIGTH
  End If
 End If ; cx>0
For y = 0 To 6
 For x = 0 To 7
  checked(x,y)=0
 Next
Next
;If checkpoint(cx,cy, 0) = 0 Then checkpoint(cx,cy,1)
Checkpoint(cx,cy,1,1)  ; *********************************************************
	If TotallyClean=1
		For fx=0 To 7
		For fy=0 To 6
			If Sparkly(fx,fy)=1 Then atom(fx,fy)=0:peg(fx,fy)=0
		Next
		Next
	EndIf


End If ; mousedown

End If


For y=0 To 6
 For x = 0 To 7
  If atom(x,y)>0 Then

   a$=Bin$(peg(x,y))
   total=0
   For temp = 1 To Len(a$)
    If Mid$(a$,temp,1)=1 Then total = total+1
   Next
   If atom(x,y)-total > 0 Then 
    For t = 1 To atom(x,y)-total
     DrawImage electron_sprites, 64+x*space,16+y*space, (electron_frame + 128/(atom(x,y)-total)*t)And 127
    Next
   End If

   DrawImage atom_sprites, 64+x*space,16+y*space,atom(x,y)-1
   If peg(x,y) And PUP Then DrawImage atom_sprites, 64+x*space,16+y*space,4
   If peg(x,y) And PLEFT Then DrawImage atom_sprites, 64+x*space,16+y*space,5
   If peg(x,y) And PDOWN Then DrawImage atom_sprites, 64+x*space,16+y*space,6
   If peg(x,y) And PRIGTH Then DrawImage atom_sprites, 64+x*space,16+y*space,7
  End If
 Next
Next

If mx>63 And mx<253 And my>15 And my<183 Then
 DrawImage atom_sprites,64+Floor(cx)*space,16+Floor(cy)*space,nextAtom-1 ; draw current atom at mouse position (cursor)
End If

Flip
electron_frame = electron_frame + 3 ; adjust for animation speed
electron_frame = electron_frame And 127
Wend
End


Function checkpoint(x,y,clean,startpoint=0)
; **********************************
If startpoint=1 
	TotallyClean=1
	For fx=0 To 7
	For fy=0 To 6
		Sparkly(fx,fy)=0
	Next
	Next
EndIf


Sparkly(x,y)=1

number = 0 ; 0 = all connections made
Color 255,255,255
Rect 64+x*space,16+y*space,24,24,0
Flip


proceed=1
If atom(x,y)>0 Then
 ; find how many sides are connected
 a$=Bin$(peg(x,y))
 total=0
 For temp = 1 To Len(a$)
  If Mid$(a$,temp,1)=1 Then total = total+1
 Next
 ; if less sides than atom number, then forget everything
 If atom(x,y)-total > 0 Then proceed = 0: TotallyClean=0
End If

If checked(x,y)=1 Then proceed = 0

number=1
If proceed = 1
 checked(x,y)=1
 ; if completely connected, then check each connected side
 If (peg(x,y) And PUP) Then number = checkpoint(x,y-1,clean)
 If (peg(x,y) And PDOWN) Then number = checkpoint(x,y+1,clean)
 If (peg(x,y) And PLEFT) Then number = checkpoint(x-1,y,clean)
 If (peg(x,y) And PRIGTH) Then number = checkpoint(x+1,y,clean)
End If

; If clean = 1 Then atom(x,y) = 0

Return number
End Function[/code]


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