After finding some moderate success on the original Wii in 2009, Tank! Tank! Tank! has been rereleased on the Wii U, but this time it’s free-to-play. As with all FTP games, Tank! Tank! Tank! has a number of different modes / content you can buy for an additional fee, but you can still get a fair amount of value from the base game.
In addition to giving the game away for free, you can also score some Club Nintendo coins if you’re into that thing. Also while you’re looking at the eshop, you might as well pick up Rayman Legends Challenge App while you’re there, since that also has a fair amount of value at no cost.