A Walk in the Park

For block types not allowed at all in a level, skipping those block types would be better than what it does at present - placing a red highlighted block, and showing a warning instead of moving the cursor or starting the level.

A puzzle with only one space to place a block can't teach the lesson that this isn't a "place blocks anywhere" game, and "move cursor" not working looks like a bug to a player who hasn't learned that - the first level needs at least two spaces for blocks.

Some other feedback:
> Not sure if this is a bug or not, but if you walk into a gem already placed in the goal whilst carrying a gem, the second gem gets absorbed in too, and the man turns around empty-handed.