We can't teach here every game, especially because we don't share our Codes.
Every game is different, not every game the Method for Damage is " get_damage" , you need to find out by yourself.
That is the hard thing in modding.
Modding is trying, failing,trying, failing, trying, success.
No one can know if this or that function is really the right function, we are not the developer.
Start with easy Games like Subway Surfer until you have earned some knowledge about modding and general about programming stuff.