_Slydris_ is a falling block puzzle game. As with most Tetris-style puzzlers,
blocks fall down into the game area and must be cleared by completing full
rows. If the blocks reach the top of the game area and there is no more room
in the game area for the next row of blocks to drop into, the game is over.
The twist in _Slydris_ is in the player’s ability to manipulate not only the
falling blocks, but the already fallen blocks as well. If a fallen block has
any empty spaces around it in its row, it can be moved into those spaces. This
can potentially free up room for the blocks above the moved block to drop down
into the vacated space.

Each block comes in one of two colors. If a cleared row contains blocks of
only one color, one of the next blocks to fall down will be a color shatter
block. When a color shatter block is cleared, all blocks of the same color are
shattered into 1×1 blocks. There is also a bomb meter which fills up as the
player clears rows. Once full, a bomb can be triggered to remove any three
adjacent rows of blocks in the game area, draining the meter entirely with
each use.

Every once in a while, one of three special blocks appears to provide extra
challenge:

* _Growth_ : blocks grow out of the bottom of the game area, pushing blocks above them upward.

* _Locked_ : blocks cannot be moved by the player. They are affected by gravity and will fall if there is a large enough empty space below them.

* _Magnet_ : blocks can be moved left and right by the player, but are unaffected by gravity after the initial landing and will stick to the same row.

There are three game modes:

* _Infinite_ – Every time a player moves a block, another row of blocks falls down. The next row to fall is visible at the top of the game area, and the player can choose choose to move one of the blocks in that row or one of the blocks on the ground. The player has unlimited time to decide on the best move to make.

* _Survival_ – The player has a limited time to move as many blocks as he can, after which several rows of blocks fall down. The number of falling rows falling at a time increases with each level increase.

* _Zen_ – A significantly easier version of _Infinite_.