If you haven’t been paying attention to Klei Entertainment’s creations for the past few years, you’re missing out on some of the best games in the world. This year’s Invisible, Inc. [official site], recently expanded in fine style, might be the best turn-based game I’ve discovered since I joined the Chess Club all those years ago, and Mark of the Ninja is a completely different but almost equally brilliant rewrite of the stealth genre. All of the studio’s games are free to play on Steam this weekend, starting right now, with discounts should you wish to buy them after having a taste.