It is never really necessary to use a tiled map. For anything. However, it is helpful for many scenarios.
So, in your case no it is not necessary. There are many other ways you can implement a repeating background or whatever.
No, a tiled map not necessary for your arena + long path concept, but it could work okay for that concept, if you wanted to. Yes, you can add a background image instead.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.