Update this Game

I have always loved this game since it came out until the last update (3 years ago) with iOS 8 everything was ok.
When iOS 11 came up the game stopped working, now we are in iOS 11.2.1 and it looks like there isn’t more update.
Why you guys can’t update this game?

Emmanue1 about Gangstar Rio: City of Saints, v1.4.1