If you've ever felt like puzzle games are just too easy, have I ever got the game for you. Quantro follows a familiar gaming trope pioneered by Tetris decades ago. Blocks fall from the top of the screen and you line them up into rows to clear them. Easy, right? Quantro makes it interesting by confronting you with two overlapping games simultaneously.
The two games are color-coded, with the red blocks in front and the blue ones behind. At first you get alternating red and blue units to drop into place. Perhaps you'll start thinking at this point that Quantro won't be so difficult. Then the combo blocks of both colors start appearing, and your higher brain functions will be arrested by the insanity. There are 36 unique pieces that can rain down upon you. There are even some special blocks that affect both independent games.
You can play Quantro in both single and multiplayer modes. The multiplayer works over local Wi-Fi or via the internet. The game will save your progress automatically, so you can bail any time your brain needs a rest -- and it will. Quantro is free to download, but has some ads. An in-app purchase of $2 will remove them, though. It's not often that I find a puzzle game that breaks my brain in such a fundamental way, so you should check it out if only for the experience.