Some ideas about new block types

Few weeks ago I uploaded a version which supports player state saving/loading and swapping of player's and shadow's state, and checkpoint tile was added.
However, the checkpoint just save the state automatically when the player enters it.
I think it's better that when player in a checkpoint it won't save game automatically, unless you press F2 key (or some other key, e.g. down key)
And how about add a tile that enables the swapping of player's and shadow's state, if you're in the tile and press down key?
And moving blocks and spikes, and so on ... Any other ideas?
However, the checkpoint just save the state automatically when the player enters it.
I think it's better that when player in a checkpoint it won't save game automatically, unless you press F2 key (or some other key, e.g. down key)
And how about add a tile that enables the swapping of player's and shadow's state, if you're in the tile and press down key?
And moving blocks and spikes, and so on ... Any other ideas?