Megadrive/Genesis game, released 1993.
A bastardisation. When Puyo Puyo became immensely popular in Japan, Sega of America chose to release a translation, essentially the same, but with the deeply Japanese characters replaced with more "marketable" characters from The Adventures of Sonic The Hedgehog, a cartoon which is itself often regarded as a bastardisation and a cheap cash-in.
The concept is identical to that of Puyo Puyo: pairs of beans in various colours fall from the top of a pit six squares wide by twelve high, and may be rotated and shifted left and right as they fall. To remove beans, you must arrange four or more of the same colour so they connect.
When beans disappear, those above them fall down to fill the space left behind, and a few transparent "refugee" beans fall into your opponent's pit. These can only be removed by taking out normal beans adjacent to them. This is important, as the object of the game is to have your opponent stack beans over the top of his pit and lose.
The fun part comes next. It's possible to set up chain reactions, so that beans falling to fill the void from one removal are set up for another. The longer a chain reaction continues for, the more evil transparent beans fall on your opponent's side once it ends, with the pile accumulating to frankly ludicrously apocalyptic proportions, often winning the game in one crushing blow. Successful execution of such a manoeuvre is generally extremely gratifying for the player. To be the unfortunate stooge on the receiving end of such a combo can be utterly heartbreaking.
Looking past the unpleasant front, this is a fantastically addictive game with one of the greatest two-player modes imaginable. However, the truly (ahem) 1337 may prefer the glorious incomprehensibility of the Nipponese original for the sake of completeness. It's a personal choice.