From Hard Drop Tetris Wiki
A 5 bag solution for Playing Forever was discovered by QM in 2014. It requires at least 4 piece previews to guarantee success.
This is the minimum amount of pieces possible for the Playing forever loop, as a loop must use at least 35 pieces (5 bags). To avoid parity issues with the odd amount of T pieces, a skim is done in bag 2 using the T piece.
First Bag
Build this whenever possible:
If needed, the ILJO square can be built in a different way as long as it remains as a 4x4 square. If you can't build the above shape (this is rare) place the I piece to the right Second Bag The second bag is built differently based on whether the ILJO square was completed successfully or not. Case A - The ILJO bag was built correctly Resulting field: If needed, the LOJ box can be flipped The T piece should be used to skim before placing the I piece
Build this shape and hold the T piece Resulting field: Then, the T piece should be placed in one of these two ways, dependent on the order of Bag 3: T facing to the left T facing to the right | ||||||||