Perimeter

A medley of puzzles (spatial reasoning, algebra, lateral thinking) wrapped up in proceduralism and cosmic horror. It's stylish and a little tricky—you have to intuit the rules as you go along, and how the rules of different puzzles interact with each other as the puzzles start to combine. However, the story's thin and the few opportunities the game has to add more detail are instead almost entirely functional (e.g. the message system just gives you hints/answers without letting you really talk to anyone). That leaves no room for surprises unless you're entirely new to cosmic horror or folklore about sealed evils. It's still a clever set of puzzles, though, and apparently a proof of concept for something bigger.