Name ideas:

• Diamondback Railroad

• A grid consisting of a matrix of squares.
• A perimeter of squares that runs around the grid. The background color of the perimiter is set differently from the grid to tell them apart.
• Around the perimeter is a frame that provides a decorative border around the game. I'm thinking about extending the right or bottom siide of the frame to contain a console to control the game.
• The board consists of the combination of the grid and perimeter.
• Pieces numbered in ascending order. Each piece occupies a square on the board. There are no pieces in the perimeter at the beginning of the game nor at the end; the perimeter is used for "temporary" piece transit during the game.

There are less pieces than squares, so there are empty squares in the grid.

The object of the game is to move the pieces around on the board so that they are packed at the top of the board in ascending order

Hence, if we start with an initial game of:

|---|---|---|
| - | 4 | - |
|---|---|---|
| 3 | - | 5 |
|---|---|---|
| - | 1 | 2 |
|---|---|---|

the objective is to move them around until you have

|---|---|---|
| 1 | 2 | 3 |
|---|---|---|
| - | 5 | 4 |
|---|---|---|
| - | - | - |
|---|---|---|

There are movement rules.

The difficulty of the game is increased by initially providing more pieces to constrict movement.

For difficult games (meaning initially having so many pieces that there are few empty squares), a perimiter of empty squares is provided around the grid.

For example:

|---|---|---|---|---|
|   |   |   |   |   |
|---|---|---|---|---|
|   | - | 4 | - |   |
|---|---|---|---|---|
|   | 3 | - | 5 |   |
|---|---|---|---|---|
|   | - | 1 | 2 |   |
|---|---|---|---|---|
|   |   |   |   |   |
|---|---|---|---|---|

In this game, pieces can temporarily be moved onto the perimiter on their way to their final locations.

Sequence

A sequence of pieces whose names are in sequence. The pieces on the sequence are horizontally and/or vertically adjacent.

Minimum Sequence Size

The required minimum number of pieces in a sequence for it to be moveable

Implication: At the beginning of the game, a sequence of a minimum sequence size must already exist on the board

• A sequence can be dragged from either end of the sequence.
• The end is dragged one grid square at a time either horizontally or vertically but not diagnally. The end piece dragged is called the head of the sequence and the remaining pieces are called the tail.
• Each piece in the sequence follows the grid square of its adjacent parent piece when moved. I.e. each piece "lands" in the exact path of its parent piece ahead of it. The head piece has no parent.

In this way, it can be moved from one side of the grid to the other.

Presume the minimum sequence length is 3.

Given the game-in-progress:

|---|---|---|---|---|
|   |   |   |   |   |
|---|---|---|---|---|
|   | - | 6 | 4 |   |
|---|---|---|---|---|
|   | 5 | - | 3 |   |
|---|---|---|---|---|
|   | - | 1 | 2 |   |
|---|---|---|---|---|
|   |   |   |   |   |
|---|---|---|---|---|

If I split the sequence 1,2,3,4 by dragging the piece labeled "2" down one square, then the game will look like:

|---|---|---|---|---|
|   |   |   |   |   |
|---|---|---|---|---|
|   | - | 6 | - |   |
|---|---|---|---|---|
|   | 5 | - | 4 |   |
|---|---|---|---|---|
|   | - | 1 | 3 |   |
|---|---|---|---|---|
|   |   |   | 2 |   |
|---|---|---|---|---|

What just happened?

1. The player dragged the piece labeled "2" down one square.
2. The game examined the two resulting sequences:
   • 1,2
   • 2,3,4
3. Since the minimum sequence length is 3, it preserved the length by choosing the longer sequence 2,3,4.
4. If both resulting sequences satisfy the minimu sequence length, then the game will ask the player which sequence he prefers.

The purpose of this is to allow dragging smaller sequences so that the resulting sequence can fit inside the inner grid when there would otherwise not be sufficient empty squares to complete the maneuver.

When a sequence of pieces is moved by "dragging" the head of the sequence horizontally or vertically, the last piece in the tail may pass adjacently to a next piece. When this happens, the next piece is automatically added to the end of the tail. If the next piece is also the head of a sequence, then its tail is "dragged" along alos.

Example: Reconnect the two sequences we created in the previous example.

Given:

|---|---|---|---|---|
|   |   |   |   |   |
|---|---|---|---|---|
|   | - | 6 | - |   |
|---|---|---|---|---|
|   | 5 | - | 4 |   |
|---|---|---|---|---|
|   | - | 1 | 3 |   |
|---|---|---|---|---|
|   |   |   | 2 |   |
|---|---|---|---|---|

If the player moves the piece "4" up one square, the result will look as it did before.

|---|---|---|---|---|
|   |   |   |   |   |
|---|---|---|---|---|
|   | - | 6 | 4 |   |
|---|---|---|---|---|
|   | 5 | - | 3 |   |
|---|---|---|---|---|
|   | - | 1 | 2 |   |
|---|---|---|---|---|
|   |   |   |   |   |
|---|---|---|---|---|

And, if he drags the "4" up one more square, observe the "1" follow behind:

|---|---|---|---|---|
|   |   |   | 4 |   |
|---|---|---|---|---|
|   | - | 6 | 3 |   |
|---|---|---|---|---|
|   | 5 | - | 2 |   |
|---|---|---|---|---|
|   | - | - | 1 |   |
|---|---|---|---|---|
|   |   |   |   |   |
|---|---|---|---|---|

If this is only a logical game, it's likely to be really boring looking. The following are ideas to "zing" up the appearance:

• Each piece is shown in a diamond background. Its "ID" is shown in the middle of it.
• Moving a sequence is a smooth transition over a period of time.
• When a diamond is dragged around a corner, its slanting edge "slides" on the opposite edge of the diamond of its sibling integer.
• Visual highlighting shows a sequence on the grid. Part of the highlighting is that the background of the diamond is a color that is only slightly different from its parent.

There is a separate module that calculates the smooth gradient of the background color. Each piece's color is calculated using the following algorithm:

1. Divide the total piece count by 3; call this the phase count. So if there is a total of 81 pieces, then the phase count is 27.
2. Presume that each color has 256 shades.
3. Initialize the 3 colors to their initial values. For illustrative purposes, presume that we're setting each of the colors to a non-zero minimum value (don't want to start w/ black), say 0x20.
4. Select a non-saturated maximum value for each color, say 0xE0.
5. Divide the range within the minimum and maximum values by the phase count. This is the phase step value.
6. Each piece's background color is different from its parent by the phase step value in one or two of its background colors.
7. Hence, in the first of the 3 phases, the color of each piece is changed by phase step for phase count times for one of the colors, say red.
8. In the next of the 3 phases, the gradient is subtracted for red but added for green.
9. Im the last of the 3 phases, the gradient is subtracted for green but added for blue. During this time, red stays at its minimum value.

We'll probably want to experiement with this.