Unlike your common unilateral falling block games, 'Double Cross'
implements a bidirectional paradigm expanding the genre in both
dimension and difficulty.
Blocks fall from the top and fly in from the side settling in a joined
"play area". Deletions occur when rows of ten blocks are completed.
A horizontal row of 10 will cause the blocks to fall down, and
a vertical row of 10 will cause the blocks to "fall" to the right.
If a vertical row is completed during a vertical drop or a horizontal
row is completed during a horizontal drop the corresponding deletion
will not occur until the next turn. This can and will lead to
non-intuitive results. Focus on the vertical alone and you will die
from horizontal negligence and vice versa.