Write a letter inside a table cell just by clicking on it - cellsweeper

Dear excelforum community,
I have created a little cellsweeper game in excel.
The player can uncover the game-area by typing the letter "p" into choosen table cells. It would be much cooler if the game area could be uncovered just by clicking on the cells. Is there a way to do so?

Cellsweeper.xlsm

This is the file that contains the game.