Killzone: Shadow Fall: Intercept is now available as a standalone release via the PlayStation Store.
The four-player co-operative experience is a satisfying addition to the campaign and competitive multiplayer modes. It places a heavy emphasis on teamwork and features a compelling risk/reward system that ratchets up the tension amidst the never-ending stream of Helghast hordes.
Whether Intercept is worth the $19.99 asking price is open to debate, though. As much as I enjoy it, that valuation seems a tad steep for something so thin and limited in scope -- especially considering the full game doesn't cost much more than that at retail these days.