I still enjoy playing chess at the age of ninety four.Those contemporary opponents I used to play with have all passed away without me even getting even scores with any of them. On my spare time I just play a game or two against myself or the computer. Yesterday, while I'm on the middle of the game in deep thought my wife called to remind me to take the medicines. So I did. But when I returned to the chessboard, I can't remember what is the last move I made for either side and whose move it should be. That gave me an idea. What if I spin a coin to decide whose move is it? Will it be more interesting to play none turn-base chess with balanced skill vs. luck? Let's see. With all regular rules applied, starting with initial position, the first move depends on head or tail result of the coin spin. Next move likewise and so on until white/black wins or draw. While in case a player's King is in check, it is his turn to make a move unless it is a checkmate.
Suppose I want to help win against myself in five or less coin spins, what is the maximum probability that I can make a checkmate?