Snakebird

Snakebird builds its puzzles from a few rules with sharp limits. The bird's body follows its head, gravity pulls it down, and eating fruit makes it longer. Mark Brown calls growth both a blessing and a curse, since every fruit changes what moves are possible.

Brown groups Snakebird's odd movement with mechanics like time travel: the cleverer the main mechanic and its limits, the more puzzles it can support and the harder they can get. "These rules, and perhaps more importantly these limitations, are used to create puzzles."

Level 10 lures players into a wrong plan, then teaches movement. Level 10 has two fruits, and the bottom one is out of reach if the bird is too short. Players assume they can eat the left fruit first, drop down and turn back, but that makes them too long to turn, so they must approach from a very different angle.

Brown uses it as an example of assumption, catch and revelation working in one puzzle: the catch is being either too short or too long for the bottom fruit. "Not only is it a clever solution, but it's also subtly revelatory as it teaches you important stuff about how Snakebirds move," and that knowledge carries into later levels.

Hidden rule consequences become reusable tricks across later levels. In Snakebird the bird can change shape and fall in the same turn, which lets players build shapes that shield it from spikes.

Brown cites this as a revelation: a consequence of the rules the player discovers and can reuse, rather than a trick they could not have guessed.