Free app won't open on iPhone since restore

Hello,

I had to restore my iPhone 5S after the latest iOS update 7.0.5

I used to have an app called CityMapper (free app) on my phone before it crashed but since the restore it doesn't show on my phone. If I search for it in the app store on my phone it gives the option to 'open' and the app appears on my iTunes on my Mac but no matter what I do it won't open or appear on my iPhone.

Any ideas anyone?