Tetrisphere

Released exclusively on the Nintendo 64, this game is almost entirely different from the standard Tetris formula. It started out as an Atari Jaguar game titled Phear, on display at CES '95. Nintendo bought the rights to the game from its developer, and released it two years later as Tetrisphere.

Gameplay
Instead of starting with an empty playfield and placing pieces, each level consists of a core surrounded by layers of pieces. Although the game's playfield appears to be a sphere, it is actually a 32x32 square grid, with the west and east sides connected and the north and south sides connected. No matter which direction the player moves around the field, the pieces remain in the same orientation.

The objective in most game modes is to clear pieces from each layer of the game field, exposing enough of the core to free the robot trapped inside. This is accomplished by dropping pieces to form a group of three or more of the same type, to clear those and any other identical pieces touching the first group. The cursor shows where the current piece will be placed, and this cursor can be moved around with the digital control pad. The cursor will turn bright if placing the piece will start a reaction. Pieces are placed by pressing the A button, and it is possible to slide pieces of the same type as the current piece by moving the cursor over them and holding B. When holding B over a movable piece, the control pad can be used to move the piece. A piece preview on the lower left corner of the screen shows the piece currently held, as well as the next two pieces.

The player has three lives to complete each level. Placing a piece where it will not start a reaction takes away one life. If a piece is on a high enough layer that it flashes red, then placing a piece on it will also take away a life, even if normally it would start a reaction. There is also a multi-colored timer, which ticks down when the player is not clearing pieces. If the blue timer runs out, the yellow timer will start ticking, and the camera will slowly zoom towards the field. If it hits the field, the player loses a life.

For each game mode, the player can select one of several characters to play as. Each character has two statistics, both of which influence the auto-repeat rate of cursor movement under different conditions. Speed determines how fast the cursor will move normally, and Power determines how fast it will move when sliding a piece. This does not limit how rapidly the player can tap the control pad to move the cursor, however.

Pieces
There are six types of pieces in total, and any gaps between pieces on the field are initially filled by 1x1 crystal pieces. Usually, levels don't use all six types of pieces at the same time. Crystal pieces can be broken by sliding other pieces into them, or clearing other pieces next to them. To count as "next to", edges must match fully. That means that for the I and O pieces, they don't match if they're placed offset to each other -- T, Z and L with their jagged edges aren't as stringent (even the two-block-side of the Z piece can be offset in either direction). Above each other, though, pieces must match fully. Pieces always have the same rotation. There are three tetrominos: blue O pieces, red T pieces and cyan Z pieces. There are three triminos, green longitudinal I, yellow latitudinal I, and a pink three-block-corner, sort of like a truncated L. Sometimes the player will receive a wild card piece. This piece can be dropped as any type of piece, and can be used to slide any piece on the field.

Power Pieces and Special Combos
Every time pieces are cleared from the field, certain remaining pieces will be transformed into glowing Power Pieces. These can slide up over other pieces, one layer at a time. Also, clearing a Power Piece replenishes the timer greatly, and reactions started with a Power Piece take longer to clear than normal reactions, which makes it easier to start another combo while the first is still clearing. Specifically, every time 19 or fewer pieces are cleared, that same number of sparks fall to the field, and each one that touches a normal piece transforms it into a Power Piece. A spark will have no effect if it touches a Power Piece, the core of the field, or a crystal piece. The player can move the cursor to loosely determine where the sparks will land. A Power Piece can be obtained without having to clear pieces by moving the cursor over a like-shaped formation of crystal pieces, and pressing B.

Two types of special combos can increase the player's X count, which acts as a multiplier to points earned from clearing pieces. A Gravity Combo can be executed by causing one piece to fall and form a group, by either clearing or sliding a piece that is holding it up. A Fuse Combo can be executed by starting a reaction with a Power Piece, then grabbing one of the flashing pieces (referred to as a Fuse) with B before it gets cleared, and sliding it to another group.

Magic
If a combo of 20 or more pieces is cleared, the player receives a Magic power-up. If the player already has Magic, it is upgraded to the next level. A bar underneath the combo counter also fills up as pieces are cleared, and will give the player a Magic power-up when it is filled completely. Magic can be used to clear pieces and reach the core quickly. Sometimes a 1x1 magic crystal can be found on the game field, and it will give the player Magic or upgrade their current one if broken open. The Rocket will clear a small area on the top layer. The Dynamite splits into five pieces to cover a wider area than the Rocket. The Magnet rapidly zaps away pieces over the spot that is targeted. The Molecule will remove the entire top layer of pieces from the field. The Atom Bomb creates a deeper explosion that reaches through multiple layers. The Laser acts like a much more powerful version of the Magnet.

Game Modes
Practice Mode can be selected from the main menu. In this mode, the player can set up a level with any of the six piece types (at least two must be selected), 2 to 5 layers of pieces, and a requirement to expose anywhere from 1 to 99 sections of the core to clear the level. In Practice Mode, there is no time limit.

Rescue is the basic game mode, in which the player clears levels by exposing the core of each one to free the robots trapped inside them.

Hide and Seek is similar to Rescue, but each stage can have one of many special objectives assigned to it. For instance, the player might be required to expose the core around a tower placed somewhere on the gamefield, or clear out the pieces underneath a brick for it to touch the core.

In Time Trial mode, the idea is to go through stages as fast as possible, earning points and clearing stages until the timer reaches zero.

In Puzzle mode, each level has a configuration of pieces, and the player must clear them all, using a given number of slides and drops. There is no time limit, and every piece is a wild card piece. The camera can also be zoomed in and out by pressing L and R, to aid in determining the layout of pieces. A puzzle can be restarted with C-up if you make a mistake.

In Vs. Mode, the player can compete against either another player or the CPU, trying to reach the core of their gamefield first. When enough pieces are cleared, dark pieces will be sent to the opponent's field. These cannot be cleared directly, but must be cleared by adjacent pieces. Each round ends when one player exposes enough sections of their core, or loses all three of their lives. Increasing the X Count multiplier boosts the amount of dark pieces sent to the opponent.