Rack Up Treasures

The player found a Book with guidance of the main Pharaoh secret - the path to the tomb with huge room of treasures! He gets into a «generous» tomb and tries to carry away as much treasure as possible. To do this, he needs to properly fold the suitcase.
The suitcase has treasures in the form of Tetris parts. When the player picks up a part, a new one arrives on the conveyor.
You need to stack the treasures so that there are as few empty cells as possible. You can turn over already folded parts. When the field is filled at least 80%, the player enters another tomb.