Hi there again!
App aside, you can store whatever you wish in icloud, but you can't have visible access to stuff.
If you go to your phone to Settings - Icloud, you can see what exactly you can turn ON (which means what will be stored into icloud for a future RESTORE BACKUP FROM ICLOUD).
If you see the Documents and Data and go to it, you can see all the applications on your phone, and choose which to turn on or off in order to save those apps' data into icloud.
I checked mine out and when I did a restore from icloud, everything was in place (including documents, game scores and so on).