Strange battle

As I walked onto the battlefield, I noticed that something was strange. There were patches of light and dark ground, and there was something else strange too.

I tried to move forward, but the king stopped me and whispered into my ear.

"You can't move yet. Only one person at a time can move."

As I was trying to make sense out of what he said, I was approached by a foot-soldier. I tried to question him, but he responded, "I follow orders. My orders are to move forward only. If I get to the other side, I can get promoted and possibly get a random gender change. Then I may be able to tell you more."

Just then, a knight riding a horse leapt out behind me, muttering something that sounded like "Why can't you move forward like a normal horse?"

Then a religious-looking person came into my view.

"They use priests to fight?" I whispered to the knight.

"Those are not just ordinary priests", said the knight. "Those are bishops. And yes, they do fight, in the name of the holy diagonals."

I noticed a heavily fortified chariot roll past.

I tried to move forward. "NO!" said the king. "You'll put me in check!"

"Even better", said the other king, as a queen moved in an oddly straight line. "Checkmate!"