The "I'm done" and "Guess" buttons are confusing.

"I'm done" can be replaced with "Give up and see answer" (Yep, it's an horrible name, try to find something shorter.)

I don't have a good suggestion for "Guess". I tried writing multiple words in the text box. Perhaps you can use JavaScript to ban spaces in the test box.

Also, perhaps you can change the game, so it says it's a success when you guess 5 labels. People really like to win, and sometimes getting all the label is boring.