Tetris (Atari)

Tetris (styled TETЯIS) is a puzzle game developed by Atari Games and originally released for arcades in 1988. Based on Alexey Pajitnov's Tetris, Atari's version features the same gameplay as the computer editions of the game, as players must stack differently shaped falling blocks to form and eliminate horizontal lines from the playing field. The game features several difficulty levels and two-player simultaneous play. Atari later ported the game to the NES and released an unlicensed NES version in 1989 under its Tengen brand.

The game ran in B-type mode, where each level was cleared after 10 or more lines, and points were awarded for each empty row at the top of the playfield. Challenges included various patterns of starting garbage and randomly appearing single blocks in the playfield.

Rotation system
The rotation rules are identical to those of Tengen's NES port, except the tetrominoes are colored differently, and they do not change color once they lock. In addition, the player can rotate the tetrominoes only counterclockwise.
 * Pieces spawn with left side of bounding box at column 5 and top at row 22.
 * Rotations in all states touch left and top of bounding box. Exception: vertical I, which is placed in the second column from the left.
 * There is a 1 square to the left wallkick rule.

Because basic rotation can fail when a piece is against the right wall, but not when the same piece is against the left wall, this game will wallkick one square to the left if basic rotation fails. If that fails the piece will not rotate. This allows for a few very unique wallkicks.

Gameplay
The arcade game only offers a "B-type" mode of play. Each level has a number of lines to clear. Once this number is reached, the player is taken to the next level. In each loop, every three levels has a special gimmick added in an attempt to make the gameplay harder: On Level 19 and up, the game combines "Handicap Start" with "Added Blcoks".
 * Levels 1-3: Nothing
 * Levels 4-6: "Handicap Start": The level begins with blocks already present on the playfield. Level 4 places eight blocks stacked directly next to the left and right walls, Level 5 has several blocks floating, and Level 6 has a dome-shaped layout with a hollow center.
 * Levels 7-9: "Added blocks": Random blocks are added to the play field after every eight blocks placed. Level 8 decreases this to every six blocks, and Level 9 decreases it to every three. Once a certain number of blocks have been added, no more will spawn.
 * Levels 10-12: "Advancing Lines": Lines of Garbage will slowly build up under the player as they drop pieces. Most lines will have more than one missing block, and if the blocks reach a certain height, rows will not spawn.
 * Levels 13-15: "Handicap Start II": The level begins with blocks already present on the playfield. Level 13 places two arrows pointing to each other on both sides of the play field, level 14 has six blocks arranged in a circular pattern (missing only the diagonals that would complete the circle), and Level 15 has four diagonal lines made of blocks.
 * Levels 16-18: "Best Players Initials" The play field begins with blocks that spell out the initials of the players that ranked in the top three on the game's Hi-Scores list, with Level 16 showing the player in 1st, Level 17 showing the player in 2nd, and Level 18 showing the player in 3rd.

Scoring
Next to each player's score is a horizontal bar called the rainbow meter. Every four lines cleared adds 1 to the rainbow meter. If the player tops out and continues, the rainbow meter is set the way it was before the player added.

The score for each Tetromino that the player places is d*r*(r + h), where
 * d = 1 for normal gravity or 2 for soft drop when the tetromino lands
 * r = the number of bars on the rainbow meter plus 1
 * h = the row on which the tetromino was placed, minus 1 (0 = bottom)

Line clear scores:

After finishing each round, the game awards a "BONUS FOR LOW PUZZLE" of up to 2100 points based on the number of empty rows above the highest block left in the playfield. The formula is 5*e*(e + 1), where e is the number of empty rows.

In a two-player game, finishing the level before the other player gives a 2,000 point bonus. This bonus is awarded both for skill and for putting more money into the machine.