Puyopuyo is a
highly addictive puzzle game from
Compile, a
Japanese software company. It's a
puzzle game where 2 blocks (each one of several
colors) come down at once. Place these blocks, as you must
connect 4 or more
blocks and make
chains to
get points. One wonderful
free version of it,
xpuyopuyo resides at http://
chaos2.org/.
Of course, the only experience an American will probably have with the game is "Kirby's Avalanche" -- all of the Puyo series are released only in Japan.