Would you prefer an AU situation where we use OCs?
Use different characters from the game? Like Eseld comes to New Serene looking for help instead of Siora.
Maybe a mixture of both previous ideas?
Have it set after the events of the game?
I'm with with using OC's or characters themselves but more or less in the same roles they were in the game, for example, as Constantin or De Sadet, It'd be interesting nonetheless- OC or not