Pokemon Shuffle, released on February 18, 2015, is a free-to-play download-only title on the Nintendo 3DS; right in this first sentence is everything you need to know before you download it: it's free, it's a Pokemon-themed game, and it is for the 3DS. There's really no excuse not to own it.
Of course, Pokemon Shuffle is not a traditional Pokemon RPG, rather it is a puzzle game similar to and arguably as addicting as Candy Crush (as long as Pokemon appeal to you more than candy does).
Pokemon Shuffle is broken up into puzzle-levels themed after different Pokemon. The Pokemon you are "battling" in each level appears on the top screen of your 3DS, while a grid of adorable Pokemon-face images will appear on the bottom screen. Your task is to rearrange the Pokemon faces in the grid to make rows of at least 3, if not 4 or 5, matching images. Once each row is forged, it disappears, damage is inflicted on the opposing Pokemon, and the disappeared Pokemon images are replaced with new ones. Each level is completed once the Pokemon you are battling has its HP reduced to zero.
The Pokemon that actually appear on the puzzle grid are yours to choose right from the beginning of the game. After each Pokemon you encounter is defeated, you get a chance to capture it- if you complete a level without using up all of your available moves, your chance of catching the opposing Pokemon will increase significantly. Once you capture a Pokemon, you are permitted to select that Pokemon to use in later battles. Matching Pokemon with a type-advantage over the Pokemon you are trying to defeat will do double-damage onto your opponent the same way it does in the Pokemon RPGs.
However for all that makes Pokemon Shuffle unique, there are some pretty frustrating cons that come as a result of the game being free-to-play. For example, you only get a certain number of attempts to play each level before you are forced to wait an arbitrary real-world 30 minutes, after which you are allowed to resume playing. You have the option to pay real-world currency for the time limit to be removed, but the game really isn't addicting enough to convince me to pay for additional tries. Moreover, power-ups that make completing levels easier can be purchased with coins earned by completing puzzles. Then, you are awarded with 500 coins every time you "Check In" to see the latest Pokemon Shuffle offers by connecting to the internet, but you can only check in once per day- these are the only two ways of getting coins, thus getting power-ups. This has put me in frustrating positions where my lack of power-ups and my inability to earn coins other than by checking in for several days in a row renders me unable to get past more challenging levels. Of course, there is an option to pay real-world money for power-ups.
Despite these few minor drawbacks, Pokemon Shuffle is perfectly suited for the 3DS. Everything from its art-style to its price (once again, free) is begging for you to download it and give it a shot. At its best, Pokemon Shuffle is a charming puzzle game easily accessible to fans of both Pokemon and puzzle games; at its worst, it will easily grant you the means to kill time if you've simply nothing else to play.