Great series
A shame this has been labeled as a lost cause by its rights holders in the west.
The core of the game is completing assortments of challenges in 'retro' games, which are totally original games made to resemble old arcade and home console games of the 8-16bit eras. Once you have finished all a games challenges, a new game is available with its own set. Not that you can't also play any of these games on their own: each game is quite a bit deeper than their first batch of challenges manages to get through.
The game is somewhat import friendly language wise. The challenges are of course in Japanese, and not understanding what you need to do in order to proceed can be upsetting. There is also a bit of exploring you can do in the overworld that is somewhat text heavy. In most cases the text isn't important, but often quizzes, questions or tips pop up that offer goodies or aid that can be useful if you selected the right choice. The games themselves, for the most part, are easy to play and figure out aside from the aforementioned tips and cheats explained in Japanese. Looking up a guide(If there currently are any) or keeping a translator handy wouldn't hurt.
But the language barrier isn't insurmountable, and the games themselves are quite unique. If you own a Japanese 3ds anyway you could easily do worse than to try this title out.
