I could be wrong but I’m guessing you game hasn’t been clicked on and isn’t in focus. So your program is still simulating typing but it isn’t going to the right place. There’s this concept of focus within applications. Think of when you were writing this post, how did the computer know that you didn’t want to type in the search bar? This is because the text box was in focus and not the search bar. Normally programs represent focus with the cursor. The same applies for applications. Even if your game opens in full screen that doesn’t necessarily mean that the game is in focus. You could click on it manually but if you want it fully automated then you could just use the Robot class to click. If that’s what you want, try this when your game opens:
robot.mousePress(InputEvent.BUTTON1_MASK);
robot.mouseRelease(InputEvent.BUTTON1_MASK);