Tetris The Grand Master

Tetris The Grand Master is the first arcade game in Arika's TGM series.

Gameplay
TODO: I think we should possibly include one of those anatomy screenshot dealies that points everything out (score, grade, time, and level). Sort of like in the IRS patent. Maybe with a caption that says "beginners should care most about level, while advanced players care only about their time". Or something.

Unlike typical tetris games where the goal is indefinite survival and a high score, TGM is a challenge where you have a finite opportunity to attain a high Grade. With the exception of the final grade of Grand Master, grade is derived from your score. This indirectly makes the grading system strongly favour survival, with a special emphasis on clearing non-singles late in the game during 20g.

With only a small number of grades, there are often ties. The highscore table ranks a tied grade higher if it was attained faster. In practice, solid play will award players the highest rank of Grand Master. As such, for adequately skilled players the game becomes a time attack to level 999.

Level
Level has a unique implementation in TGM. The level counter will increase by 1 for every piece that enters the well. It will also increase by 1 for each line cleared. The game ends once level 999 is reached.

When you are about to increment the hundreds digit (eg. at level 399), only line clears will count towards your level. Level 998 is treated similarly, with a final line clear required to reach 999 and finish.

Speed
Gravity does not increase uniformly, unlike many other tetris games. It rises and falls, depending on the level, as follows:

The player can force constant 20G, by entering a code before starting the game, though this will exclude their play from the highscore list. Unlike TGM2, the line clear delay, lock delay, ARE and DAS do not change throughout the game.
 * Line clear delay is fixed at 40 frames.
 * Lock delay is fixed at 30 frames.
 * There are 25 frames of ARE during which DAS can be charged.
 * DAS is fixed at 16 frames (inclusive of both the initial shift and the autoshift frames).
 * In addition, there are also 3 frames of "lock-flash"; 3 frames of delay after ARE but before the appearance of the next tetromino (during which DAS will not charge); and 1 frame of delay before line clear animation begins.

Scoring
TGM shares the same scoring gimmicks of many other Tetris games, though they are not quite implemented the same way:
 * You receive more points for clearing more lines at once.
 * Lines are worth more with each passing level. (The nature of "level" in TGM, however, means the amount of points a line is worth is constantly changing.)
 * You receive points for forcing a piece down. (Though only when this results in cleared lines, unlike in several other games.)

There are a few scoring gimmicks unique to TGM:
 * You receive a combo bonus for clearing lines with consecutive pieces.
 * You receive a bravo bonus for clearing the entire screen.

Incidentally, for all players good enough to attain the rank of S9 score becomes irrelevant and the focus changes to a time attack rather than a score attack. Nevertheless, here is a more technical description of the scoring formula:

Score = ((Level + Lines)/4 + Drop) x Lines x Combo x Bravo

Where:
 * Level is the current level you are on.
 * Lines is the number of lines you just cleared.
 * (Level + Lines)/4 is rounded up.
 * Drop is the number of spaces you manually dropped the piece. The last space your piece falls does not contribute to this, however locking the piece once it has landed will add 1 to the Drop.
 * If the previous tetromino cleared 0 lines, Combo is 1. Otherwise, if the previous tetromino cleared L lines, and its Combo value was lastCombo, the Combo value for this piece is:
 * Combo = lastCombo - 1 + (2 x L - 1)
 * Example: A double-single combo will have a combo 1 for the first line clear and 3 for the second.
 * Bravo is equal to 4 if this piece has cleared the screen, and otherwise is 1.

Grading
In TGM1 grade is entirely determined by score. As you pass certain milestones, TGM will assign you the next grade:

Grand Master rank has four requirements:
 * 1) At level 300, score is at least 12,000 (grade 1).
 * 2) At level 500, score is at least 40,000 (grade S4).
 * 3) At level 999, score is at least 126,000 (slightly higher than grade S9).
 * 4) At level 999, time is 13:30.00 or less.

Codes
All codes should be entered at the title screen.

Key: L = Left, D = Down, U = Up, R = Right
 * TLS Mode: ABCCBAACB
 * 20G Mode：DDDDDDDDCBA
 * Big Mode: LLLLDCBA
 * Uki Mode：ABABABABABABABABB
 * Reverse Mode: DUUDCBA
 * Monochrome Mode: RRRUCBA