One of the interesting things about this game that sets it apart from most others, and especially sets it apart from most incest games, is that the player isn't really actively pursuing Haley, even though that's the titular and obvious goal. Yes, there are point-acquiring choices along the way, but they're almost all about being a good brother, being a nice guy, being there for her when she needs you, etc. Until this most recent release there are no choices in which "I'm romantically and/or sexually interested in my sister" is represented by an active decision to be made by the player. Instead, the game's about watching and responding to Haley as she works through her feelings and talks herself into taking each new step. Even though the game doesn't perspective-switch, Haley's at least a clear co-MC. I'd go further and say she is the MC; we just happen to be viewing events from the perspective of a different character.