Sometimes, the free to play model allows developers to save some games headed towards ruin, at least saleswise. In free to play games, players get for free only the most basic features of a game, while they’ll have to pay for everything else, most of the times with microtransactions. Quite a few games have made the jump to a free to play model, even some big titles like Star Wars: The Old Republic.
Tank! Tank! Tank! has shifted from full paid game to a free to play one: the game didn’t really do well in Japan, judging from the Miiverse activity. Seeing the situation, Namco has turned the game into an upgradable demo: the basic game pack is available for free, supporting multiplayer and featuring the city map playable in Free For All, Team Battle and Gian Monster modes. The basic pack can only be played three times a day: buy extra downloadable content and the restriction will lift.
The DLC available for the game include extra maps and a new game mode My Kong mode made specifically for Gamepad use.
As of now, the Tank! Tank! Tank! promotion has only been announced for Japan. The extra dlc maps and modes are already available on Wii U Japanese E Shop. No news for the west are currently available.
Article from Gamersyndrome.com