I haven’t tried, but I think that this should be or int(self.text_box_user_score.text) > 100
The problem with what you are trying to do is that the user will see the text disappearing while they are typing. For example they type 123e and everything goes away.
Intercepting the last character typed and removing only that one is possible, but not easy, because one could type the e in the middle of a long number. In javascript you can intercept the keyboard events and prevent them from reaching the textbox, but I think it’s overkilling. Plus it often doesn’t feel right for the user.
I usually use the Validator dependency which will take care of showing an error message if the input is wrong.