I have been playing several games on my iphone 7 for weeks, now, when I click on the icon for the game it starts to load but then cuts off and goes right back to the desk top where the icon is. Does anyone know what I can do to fix the problem?

I have been playing several games that I downloaded on my iphone 7. I have had no problems accessing these games for the last several months. Ever since 12/24 when I click on the games icon, the game begins to load but it just goes back to my desktop and won't load. Can anyone tell me how I can fix this problem? It happens with more than one game.