This following question concerns different copyright issues.
A friend of mine and myself are planning to develop an app to facilitate a role playing game. (Most of the time it is called "Werewolf", I believe that the game "Ultimate Werewolf" is at least one of the English versions of it. It has got the same principle as a game often referred to as "Mafia".) And as we are German, we would base our app especially on one of the german versions of the game, but there are at least two german ones (3), one french (4) and an English one that I know of.
The questions that came up was: How much can we use from one of the rulebooks? Can we use the texts? Are those protected? Could we maybe even use the pictures of the cards, …? What if we would produce pictures that are clearly inspired by the images from one of the editions? What kind of laws apply, as we are developing for the whole world when we are basing us on a german version (which is produced by a french company)?
The descriptions of the different roles and the functioning of the game are for example also found on the Wikipedia page of this game.
Thank you in advance for any insight!
(Sadly I am not allowed to post the other two links to the other german and french version, the other german version (3) is found by googling "werwölfe pegasus" and the french one (4) is called "Les Loups-garous de Thiercelieux".)