Closure launched today on Steam. This is a review of the PS3 version, which was released on the PlayStation Store in North America earlier this year. There are no plans for a European PS3 release at present. The PC and Mac version supports higher resolutions and features a developer commentary and some basic mod support, but otherwise it's identical.
Speaking as a lifelong arachnophobe, I recall many a night in my youth when I'd have a hard time sleeping because there was a spider in my room. I'd keep the lights on, lie awake and observe its every move with an eagle eye. If it crawled towards the ceiling over the head of the bed I'd reposition myself at the foot. If it skittered towards that end I'd shuffle back. If it was a particularly restless bugger I'd sleep on the floor. I was a weird kid.
What I eventually grew to realize was that if I turned off the lights and hid under the blankets its presence bothered me that much less; out of sight, out of mind. Of course I knew it was still there, but the lack of visibility warranted a sliver of imaginative protection. Games aren't bound by this troublesome reality, and Closure goes one step further than my feeble "kill the lights" plan ever could - by envisioning a world where that which is in the dark ceases to exist.