What's this?
So, there are currently 3 games in this series.
Rhythm Tengoku for GBA (only Japanese)
Rhythm Heaven for DS
Rhythm Heaven Fever for Wii
So there are rhythm games in each of the games. All involve rhythm.
There are rows which contain 6-5 games in each row. The last game in each row is a remix of the other games in that row. There are extra rows which are essentially a harder version of older games.
Examples :
Rhythm Tengoku - Cheese Heist (fan name), Bon-Odori Dance (fan name), Tap Trial, Clappy Trio
Rhythm Heaven - Lockstep, Rockers, Drummer Duel, Love Lab
Rhythm Heaven Fever - Double Date, Ringside, Hole in One, Screwbot Factory
There is an upcoming game for the 3DS in the series which has not yet been released but will be released on June 11th in Japan. There has yet to be an announced version for an English version.
It is translated to be Rhythm Tengoku : The Best +
It contains 70 rhythm games from the previous 3 games and contains 30 new rhythm games.
Watch it on youtube if you are interested.