Currently playtime can be added under “Hours played” in 0.5 Steps. That is kina bad or annoying. Imagine you played a game for 60 hours, so you have to press the + Button 120 times.
So why not allow the user to input the playtime manually like for start- and enddate. Press the number between the - and + button and make an custom input. Defining a filter or regular expression isn’t really complicated.