Because you are too young to enjoy Game Launcher. You should give Samsung Kids a try if your phone supports it. Enable it in Quick Settings panel, you may have to add it by pressing 3 dots then select Edit buttons then select Kids then select Done. Now select Kids on Quick Settings panel and follow the prompts. You can add your games to Samsung Kid under Settings. If you do not see it then your phone do not have Samsung Kids. Here is a workaround: If you are already sign in to your device with a Samsung Account and you cannot use Game Launcher because you need to be 18 years old then try to edit your date of birth in your Samsung Account profile , choose a year that make a difference of more than 18 years with current year. Hope this helps.
