Maze

 if maze.key_needed >= 0 and maze.has_key == 1 
  maze.move(maze.key_needed) 
 endif 
 options = 0 
 n = maze.can_move.length() 
 repeat n 
  if n <> maze.from and n <> maze.key_needed and maze.can_move[n] == 1 
   options += 1 
  endif 
 endrep 
 if options == 0   # dead end 
  to_cardinal = maze.from 
  maze.move(to_cardinal) 
 endif 
 random_option ~= options 
 n = maze.can_move.length() 
 repeat n 
  to_cardinal = (maze.from+maze.can_move.length()-n) % maze.can_move.length() 
  if maze.can_move[to_cardinal] == 1 and to_cardinal <> maze.key_needed 
   if random_option == 0 
    maze.move(to_cardinal) 
   endif 
   random_option-- 
  endif 
 endrep 
 

 maze.index_north 
 maze.index_east 
 maze.index_south 
 maze.index_west 
  Index of cardinal points. 
  -> 0 north-index 
  -> 1 east-index 
  -> 2 south-index 
  -> 3 west-index 
  Constants. 
  
 maze.cell_current 
  Current position in 2D coordinates. 
  -> e.g. [0, 0] 
  
 maze.from 
  Cardinal index of previous position. 
  -> -1 if it is still at the starting position 
  -> maze.index_north if it has arrived from north 
  -> maze.index_east if it has arrived from east 
  -> maze.index_south if it has arrived from south 
  -> maze.index_west if it has arrived from west 
  
 maze.can_move[cardinal_index] 
  Check whether movement is possible 
   from the current position 
   to each cardinal_index. 
  -> 1 if it is 
  -> 0 if it is not 
  
 maze.has_key 
  Check whether key is being carried. 
  -> 1 if it is 
  -> 0 if it is not 
  
 maze.key_needed 
  Check whether the key is needed to make the next move. 
  -> -1 if the key is not needed
  -> maze.index_north if the key is needed to move north 
  -> maze.index_east if the key is needed to move east 
  -> maze.index_south if the key is needed to move south 
  -> maze.index_west if the key is needed to move west 
  
 maze.cell[cardinal_index] 
  Adjacent 2D coordinates 
   from the current position 
   to cardinal_index. 
  -> e.g. [1, 0] 
  
 maze.cells_visited 
  List of cells already visited. 
  -> e.g. [[0, 0], [1, 0]] 

 maze.move(cardinal_index) 
  Try to move to maze.cell[cardinal_index]. 
  Restart program counter. 
  Note that it increments the movement counter even if it cannot move.