Tiles are not distinguished between blocked and unblocked.

It seems provision was left for blocks to be "unwalkable" for example you shouldn't be able to walk on water or through bushes.
```
UNBLOCKED_TILES = ['00', '02', '06', '0c', '0e', '14', '18', '1a', '20', '24', '40', '4c', '53', '54', '55', '59', '5a', '5b', '5f', '60', '61', '67', '68', '69', '6d', '6e', '6f', '73', '74', '75', '7b', '7c', '7d', '81', '82', '83', '87', '88', '89', '8c', '8d', '8e', '8f', '91', '92', '93', '94', '95', '97', '98', '99', '9a', '9b', '9d']
```
But yet you still can. Can you fix this?

Search for UNBLOCKED_TILES and the movement or collision logic that decides whether a tile can be traversed. Reproduce the issue with water or bush tiles, then verify blocked tiles reject movement while the listed unblocked tiles remain traversable.

Written by the indexing model from the issue text.