What copyright issues? You make a submarine game.
And what is the problem with the EU and Germany government by making a computergame with subs?
That sounds all really strange to me.
Btw: Everyone should pay his own tax. I don't want to pay yours. Why you start a project with thoughts to avoid paying tax?
I think you should start first with making the game. If it is finished you should think about how to make money. Since kickstarter it seems the most will earn money and then make a game - but mostley they failed.
