The Tower Pack for Metro: Last Light should have arrived in your Steam window by now. It's a tower climb, a series of increasingly tough floors, setting the task of seeing how high you can climb.
It's £4/€5 (and $5, which is £3.21 and €3.79 - gee, thanks), or is the second included piece in the season pass if you so optimistically purchased that. The tower challenge will record your stats and throw them into a shared leaderboard, letting the whole thing become a competitive climb.
Next up will be The Developer Pack, which will feature a "Shooting Gallery", an AI Arena, and "Metro Museum", along with a new mission called The Spider's Nest. Then finally will be the Chronicles Pack with three new SP missions, where you'll play as Pavel, Khan & Ulman, and Anna.
Here's wot Jim thought of the game when it was released in May. Of course, this comes from publisher Deep Silver, who are still yet to get back to us about the release of Dead Island: Riptide's torso.