There's a new Killing Floor event happening with new weapons and maps and game modes and all that jazz. There's also one intriguing new achievement — unlocking it gives you a permanent free skin.
Get 4 of 6 of the 2013 Summer Event in-game level Achievements, one Standard and one Objective Mode map completion Achievement, plus the Punk'd Achievement to unlock Steampunk Mrs. Foster
The emphasized part is giving me trouble. The rest is fairly obvious (unlock Punk'd, complete KF-Steampark, complete KFO-Steampark).
What even is an "Event in-game level Achievement"? One could assume that it's the achievements that say "[2013 Summer]" in their description, but there's a grand total of 3 of those. Are some of them hidden maybe? What do I have to do?