GravBlocks is both a falling-block puzzle game (like Tetris) and a match-three puzzle game (like Pokemon Puzzle League, Bejeweled), but is also drastically different than either of those titles. The most unique aspect of GravBlocks is the aptly named Gravity Blocks. Aligning three of these blocks facing the same direction will alter gravity to that direction. So if you align three “left arrow” Gravity Blocks, then the gravity will shift to the left side of the screen, and the left wall now becomes the floor, with the opposite wall being the new ceiling where blocks drop in.
In the most basic aspect of the game (and also the original gameplay mode), players change gravity in order to build score multipliers, but must do it carefully! The walls contain hazards, and the higher the difficulty level and the longer the player plays, the more Destruction Hazards there will be to contend with! Dropping blocks into these Hazards resets the score Multiplier.
In order to survive this ordeal, players use Wild Blocks to temporarily close all the Hazards (for about 12 seconds) so that they can change gravity safely. There are also Bomb Blocks which will destroy all of one (or more, if you’re really clever) block type onscreen at once.
Source: The Developer Website.