Chess960
This is a fun, unrated, Chess960 tournament. Chess960 is standard chess, except that the pieces are shuffled randomly on the back rank to start, into one of 960 possible setups. Both sides pieces get the same shuffle, so each of your pieces faces its direct opponent, just as in regular chess. The only other change is that castling rules are modified so castling either side is still possible, even though the kings and rooks start in potentially odd positions (the king is always between the rooks though). If you castle king side, your king always goes to the g file and your rook always goes to the f file. If you castle queen side, your king always goes to the c file and your rook always goes to the d file. Just as in normal chess the king cannot castle out of check, or into check. Just as in normal chess the king cannot pass over any squares attacked by the opponent, or occupied by one of your own pieces. Because the rooks don't necessarily start in the corners, these rules might let you castle with a knight, bishop or queen in the corner you are castling towards. Or even on the b file when you are castling queenside.