The Witcher 2: Assassins of Kings Midsummer Steam Update

With the Steam summer sale started, CD Projekt has launched a Steam-only update for the Witcher 2: Assassins of Kings, an achievement-related secret you'll have to look for.
A long hot summer usually means that it's time to stop playing games and go outside, right? Wrong! A long hot summer means that it's time to take advantage of some sweet deals taking place during the Steam Summer Sale and fire up your Steam copy of (The Witcher 2: Assassins of Kings) because we've prepared something special for everyone who's bought the game on that platform. Now, it's not going to be easy to find it, but we encourage everyone to try, because there might be an achievement waiting for you down the road. Here's a little information that might help you a bit:

(Midaëte, or Midsummer, is the day of the summer solstice and marks the beginning of the first month of summer in the elven solar calendar. Elves believe that all things under the sun occur in cycles. After Midaëte the days grow shorter and the dying commences - to last until the winter solstice. Summer Shrines erected on this day give praise to the sun and life, while acknowledging death's certainty.)

We realize that the hint given above might not be much, but we're confident that you will manage to solve our little riddle anyway. Make sure to let us know in the comments, once you've figured it out. As mentioned earlier, the in-game change applies only for the Steam version of our game.