Rain World

Rain World teaches only food and leaves everything else unexplained. It explains filling your belly and hibernating, and nothing about symbols, gates or creatures. Designer Joar Jakobsson drew on being an exchange student in South Korea who could barely read signs, so the player feels like a stranger in a strange land.

The cost is that some players bounce off. Mark Brown needed two false starts himself.

Rain World keeps unknowable things, like how predators think, unexplained on purpose. The game picks what to leave ambiguous: elements that are optional or inherently unknowable, such as a predator's thinking. Mark Brown notes there is a fine line between intriguing and confusing.

His advice: "it’s important to be conscious about which elements of the game should aim for usability and which should aim for ambiguity".

Rain World's animals hunt and fight each other without needing the player. Animals hunt for food and fight rivals over territory, so the world keeps moving whether or not the player is involved. This gives the AI goals beyond attacking the player.

Mark Brown uses it as an example of AI with its own goals producing emergent moments.