All three of these are great: a crazy good tour of block pushing mechanics. Having shown my four year old a few minutes of Baba is You, he did take the lesson that rule systems can be arbitrary. Stephen's sausage roll explores edge cases remarkably well — though gets a little out of hand at the end. SnakeBird feels like a bait and switch: looks to be easy at first, then drops you into the deep end. (I won't mention the Witness because it isn't a block pushing game.)