The Talos Principle: Road to Gehenna

Basically The Talos Principle in miniature with better writing and world design. Moves past the basic conflicts of the main game to the more interesting stuff like the AI society and their perspectives on humanity and creativity. It takes the loose storytelling of the main game and compacts it, with more-complex characters and trickier stakes you actually have some say in. As for the puzzles, they're much harder on average, sometimes in fun and interesting ways and occasionally pixel-perfect bullshit (in a 3D game with clunky physics???). If you find the main game's story is too sparse and its puzzles just go on and on, try switching to Road to Gehenna early—it's a quarter of the size, but a lot denser.