tile_def$ = tile_specs$(ReadTile(x-1, y-1))

tile_def$ = "1" + Mid$(tile_def$, 2, 3)

For i = 0 To max_tiles
 If i = ReadTile(x-1, y-1) Then WriteTile(x-1, y-1, i)
Next

;  1---2
;  |   |
;  3---4
;

tile_specs$(max_tiles)
tile_specs$(0) = "0000"
tile_specs$(1) = "1111"
tile_specs$(2) = "1000"
tile_specs$(3) = "0100"

;usw.

;Dann musst du die Funktion anpassen:

Function SetTile(x, y)

 WriteTile(x, y, 1)

 AlignTile1(x, y)
 AlignTile2(x, y)
 AlignTile3(x, y)
 AlignTile4(x, y)
 AlignTile5(x, y)
 AlignTile6(x, y)
 AlignTile7(x, y)
 AlignTile8(x, y)

End Function

;---links oben
Function AlignTile1(x, y)

 tile_def$ = tile_specs$(ReadTile(x-1, y-1))

 ;---die rechte untere Ecke wird angepasst
 tile_def$ = Mid$(tile_def$, 1, 3) + "1"

 WriteTile(x-1, y-1, GetTile(tile_def$))

End Function

;hier die anderen Functions einbauen

Function GetTile(spec$)

 If spec$ = "0000" Then Return 0
 If spec$ = "1111" Then Return 1

 ;...

End Function