In Filament you play as a dungaree-wearing engineer answering a distress call from a stranded vessel called the Alabaster. You spend some time wandering the warmly lit corridors, to check out crew logs and admire the luminous planet lurking hugely beyond the windows. Treasure these moments of exploration, because you will spend most of your time guiding a little robot through dark rooms, making grumpy noises as you try to bring the ship's systems online.
Spaceships run on knots in the Filament universe. When you come across a locked door or a deactivated console your view shifts to the little robot. You have to use him to weave a glowing thread between every dormant obelisk in the room. Then you need to feed the wire out of an escape hatch to complete the puzzle.
It's a simple, intuitive system that quickly becomes difficult as the game introduces new rules. In one room certain obelisks open up doorways that let you restring your pattern to hit the remaining pillars. In another, obelisks throw up walls when you activate them. The side of the pillar the thread touches determines where the wall springs up, so you have to approach the task as though you're solving a maze as you're building it.
You can't move past your own string, of course; it's quite possible to hit every pillar in the room and wall yourself off from the exit. Luckily there are reset and rewind commands that can get you back to the start of a puzzle quickly—it's also worth pressing shift to make your robot move faster.
It's novel how the physics of the cable is important to the puzzle. You need to pay attention to the tension and direction of the wire as you weave it around each corner, to make sure the cable is pressing against the side of the obelisk you want.
Filament reminds me of The Witness, which asks you to draw routes on panels for all of its puzzles, but grows that simple concept to explore different ideas as you explore its island. It's brave to go all-in on one puzzle format, but Filament's cable-threading idea has the scope to sustain a small-ish puzzle game.