1997 MIT Mystery Hunt Puzzle 2 Solution

The across clues can be solved to yield a valid crossword puzzle with words (including some abbreviations) going across and down. The down clues can be solved to yield a valid crossword puzzle with words going across and down, but mostly not the same words. They need to be solved as two separate puzzles with the same grid, as in the Siamese Twins crossword variety.

ORE ICK  USES   INS TSK  MOPE
ANN CAN ATOLL   ROT WON TIBIA
RAVIOLI DELVE   SWAHILI WRENS
  IAN GRE VIP     BUT GPA SEE
STOP SHE JEST   MILE THE NESS
ABU ATTIRE      ARE ESTATE
CASTLE NATURE   CASTLE COWARD
   SPLEEN NOG      BITCHY SAO
TAMP LAD KING   TANS SAY KING
ALA EAR PIT     ATO GEL PEN
KITES TRADING   KATIE IMAGINE
EBERT HOW NET   ERECT CAW NEA
SIDE  YEN GEO   SIDE  OWN EDT

Six words are the same in both grids. In clue order, they spell CASTLE KING SIDE, KNIGHT TAKES PAWN, which is written as O-O, NxP in standard chess notation. OONXP is the answer to the puzzle.