As this post goes up, you've still got more than two hours left to snag The Talos Principle free of charge at the Epic Games Store. Epic will be offering the game for free until 11:00 EST / 16:00 GMT, when it'll be replaced with the next title in the 12 Days of Free Games event.
The Talos Principle is a Portal-esque puzzle game developed by Serious Sam developers Croteam. It's a major shift from Sam's madcap, nonstop shooting and noise, and instead tasks you with finding ways through mazes using various lasers, filters, and triggers. There are also ways to manipulate time, and it weaves its puzzles into a story about humanity's relationship to technology.
Our review of The Talos Principle compared it unfavourably to Portal, but there's plenty here to love even if Julian wasn't thrilled with it. The writing is interesting, with a story by Tom Jubert (who also wrote FTL and The Swapper) and Jonas Kyratzes (The Sea Will Claim Everything). It's an interesting game, and it was a genuinely new direction for Croteam to venture in.