Sliding Gems is a levels-style block-puzzle game similar to Tetris with a sliding-tiles element. The player attempts to remove 8-block horizontal lines of rectangular gemstones from a 8-block-wide playfield of two-tone squares. Their goal is to earn the highest score possible while completing a level. The player can track their level progress with a green ring that appears around the level number above the field.
The game places the gemstones onto the field by sliding new ones up from the bottom with gaps between the gems. The player must attempt to slide gemstones in left and right directions above new ones into the gaps to create the lines. When they're successful, the game removes the gemstones from one or more horizontal rows and awards points. The player tracks their score inside a circle at the top of the field, to the left of the level number.
Sliding Gems allows the player to slide tiles anywhere on the playfield, including between higher and lower tiles. It helps with aligning the tiles by presenting them with a vertical column of light around a selected tile.
Every time the player makes a move, the game adds new tiles to the playfield. As a result, they must think strategically and several moves ahead before sliding a tile into a new position or dropping it into a gap.
That said, the game also offers the player helpful tools. They can remove a tile blocking the creation of a line with a bomb. They can also break a tile into pieces to allow a piece to fall into a gap. They pay for these tools with coins they earn after they win each level.