Here's the story behind each map.

DE_CLAY:
After an intence car chase with the Counter-Terrorists, the Terrorists drive thier car into a pit in some swamp.
The Terrorists descover 2 landmarks,
and thought it would be funny if they blew one of them up with a bomb they made with parts of the car.
The Counter-Terrorists find out about the Terrorists plan and drive over to the ditch. And hopefully foil thier plans.

DE_BONEYARD:
After the death of high figure ("John Jon Johnnigson") and his horse ("John's awesome horse"),
two sites in memoriam were built; a tomb holding the body of John Jon Johnningson and his grandparents.
And a statue of Johns awesome horse.
However, John Jon Johnningson was a bit controversial in his life.
Causing a team of Terrorists to attempt to blow up one of the sites later that night.
A team of Counter-Terrorists were dispatched to the graveyard to hopefully eliminate the Terrorists.

DE_MAIZEFARM:
In the frontlines of a human vs alien war, a UFO gets shot out from the sky in a flaming rage.
Inside of this UFO is, of course, ALIENS. Still alive in the flaming wreak that is thier ship,
the aliens plan to plant a tracker in one of two locations, to guide an alien machine to thier rescue.
On the opposing force, soldiers of the humans are commanded to investigate the recent UFO reckage.
If only they knew what was going to happen...