Make your form for Pong a bit larger (Like 860x600) and start a timer, at certain intervals increase the speed of the game until a point is scored then reset the timer and reset the speed.
It seems like the color of your form doesn't change back to the default color (it stays white) after the round is complete. Also, when the user makes a guess, have it not count when they've already guessed that letter (I.e., if h is in the wrong guesses and the user does h again, have it not count)
Your program is still stuck in task manager if you close it using x
When playing a game have it so when you close it it takes you back to the game select screen instead of completely closing the game.