Secret Grade Techniques

"Secret Grade" is a hidden grading mechanism in the TGM series that rewards creating a ">" shape by leaving holes in the stack. At game over, the game evaluates the blocks in the field, looking for a zigzag pattern, and it awards a "secret grade" depending on how much of the pattern is completed. The shape may be built starting from either corner, although most people prefer to start from the bottom left.

Grading
The player is awarded a secret grade for every row of the pattern completed. A row is considered complete when all cells in that row are filled, except for the empty cell required for the pattern.

General Tips

 * Maintaining an even spread of pieces throughout the stack is very important. Uneven stacking can hinder the completion of holes and reduce placement choices near the top of the stack. Placement choices are limited near the top of the stack, so care should be taken to maintain an even stack without obstructions.


 * If it appears that the stack is growing unstable, the best strategy is to clear lines or backtrack until a stable approach can be made.

Starts
Starting the structure can be efficiently started with any piece but O. At least one line clear is required when using any other piece, but using O to create the first hole necessitates two.

Reversing the Stairs
Reaching the right wall is like starting over again; a line clear structure is needed to create the first few holes. Structures going to the right wall can be reused when returning to the left, but the pieces used must be flipped. For example, structures that used L before reaching the wall now use J on the return trip.

Base
The base is the structure directly beneath the empty cells in the pattern. Creating the correct holes in the stack is easier to accomplish when a "sawtooth" or "stairs" structure is maintained in the direction of the diagonal you are creating. By maintaining this structure, holes can be covered with others to finish holes and create the foundation for new ones. S, Z, and T are very useful for creating the sawtooth structure or covering holes, although any piece can be used to create useful structures.

Opposite Lid
Keep an eye out for ways to create covers from the other side when you get pieces in a different order. Covering with I can also be effective, but be wary when using L, J, or O; covering with these pieces can create unwanted hanging points or fill the space where you intend to form a hole.

Imperial Stairs
In the case that you have an open imperial cross or T shape, fill it with S/Z finish a hole and start another.

Cover holes with S/Z to create the foundation for new holes.

Place T next to this foundation to complete the hole and start a new one.

Hangs
Hanging points are structures that impede the direct creation of holes; pieces must instead be placed in so they are "hanging" from this structure in order to create a hole. Using O, L, or J to cover a hole have the highest potential for creating hanging points. A line clear may be necessary to continue, but sometimes "hanging" structures can be useful in quickly creating multiple holes with few pieces. If the structure is 3 units tall, only L/J can be hung from the structure and complete a hole, making a line clear the best strategy. If the structure is 2 units tall, all pieces but I can be hung from the structure to complete a hole. A few pieces will maintain the 2 unit structure, while a few will necessitate a line clear. T can successfully end the hanging structure without requiring a line clear.

In this diagram, O starts the structure and J and S maintain it. Z and L could have been used to end the structure by clearing a line, but T caps off the structure without a clear.

Line Clear
Main Article: Secret Grade Line Clear Setups

Finishes
There are very few ways to complete the pattern. The 19th hole must be covered in order to qualify for the Gm grade. For this reason, the successful completion of the pattern is dependent on receiving specific pieces depending on the current state of the stack.

The safest way to finish the pattern is to cover the sawtooth at the top with a Z, simultaneously finishing holes 18 and 19. After placing the Z, you can then proceed to fill the rest of row 19.

Riskier methods will depend on receiving one or more I blocks precisely when they are needed. An I block can spawn and move freely in row 20, enabling it to be used as a cover for the incomplete pattern.

An even riskier method involves placing a T flat over hole 18, clearing row 19, and covering hole 19 with a J.

Keep in mind that the piece that causes the game to end can also complete the pattern.

When making considerations for a potential GM solution, it may be advantageous to place L, J, and I blocks vertically on the right side of the field as you approach the top of the field. Several vertical placements of these pieces will work in parallel to fill multiple rows while leaving the spawn area open for new pieces. On the other hand, horizontal placements in the center or on the left may reduce mobility or occupy part of the spawn area.