Can't update or download the app, so I've lost my game!

[GC5410]

I opened my game for the first time in a while and it said I needed to download an update, but there is no update available. I tried deleting the game and then downloading it again, but it won't download at all - I click on the cloud icon and the download circle appears for a split second and then goes back to the iCloud icon - I've completely lost the game, please help?!

EDIT: seems it is affecting the whole of iTunes for everyone, so guess I just have to wait until Apple sort it out