And in chess, red = bad moves, green = good moves. Bad moves can setup good moves, so a sacrifice (omnibus) can setup a advantageous move or moves.
Just consolidating the Red_Castle, Green_Castle possible meanings:
Chess - Red moves = bad move. Green moves = Good moves. Castling is moving two pieces at once that allows offensive piece to be placed in more advantageous position.
Nautical - Red = left, Green = right
Literature - Red Castle = Red queen in Alice in Wonderland. Evil. Green Caste = Emerald City in Wizard of Oz. Hidden Leader pretending to be something he's not.
Military and Legal everyday life. Red = holding or stop, Green = Go.
Any others that I might be missing?