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Okay, I know this isn't official at the moment, and there's really no
point to this, but hey.

Chebble

Play on a Scrabble board.  Each player has four each of Rook, Knightrider,
and Bishop in hand, as well as one King.  Kings start in opposite corners.

Play Scrabble as usual.  Before making a play, you must move a chess
piece.  Scrabble tiles may not be played to an occupied space, and chess
pieces may not move through tiles (although Knightriders may leap them). 
Besides moving, a player may spend points they have accumulated to drop a
piece adjacent to their King.  It costs 10 points to drop a Knightrider,
20 points to drop a Bishop, and 30 points to drop a Rook.  It costs double
or triple points to drop on a premium square, depending on the premium
(double word or letter costs double, triple word or letter costs triple). 
You may not drop a piece into a position from which it immediately gives
check.

Kings may remain in check, but cannot be mated.  Instead, a player
receives a point bonus for each piece of theirs checking their opponent's
King at the end of their turn.  You receive 5 points for checking with a
Knightrider, 10 points for checking with a Bishop, and 15 points for
checking with a Rook.  Any checking piece on a letter premium square
receives an appropriate multiplier which is applied to its checking bonus.
 Any checking piece on a word premium square similarly multiplies all
checking pieces.  It is of course possible to have a checking piece have
its own multiplier as well as one or more other multipliers granted it by
other checking pieces.

Play ends when the game of Scrabble is over, after which the player with
the highest score wins.