I'm only on day 3 in two games, so can't say if it changes. But I do know that in buildings, in areas with no lights nearby, I can still see. Yes, it is somewhat dark, but I can still clearly see what is there. Outdoors, it feels like summer in Alaska, or any location above the Arctic circle.
Even if that is the case (I haven't tried it with this game), it isn't ideal to have to change brightness for each game you play. That's why many games that are intended to be dark have some form of brightness, contrast, and/or gamma adjustment built into the game. You can get what you want without having to change settings each game. Besides, I'm sure the ability to avoid the washed out effect when changing monitor brightness has a lot to do with the monitor and is probably not possible with every monitor. But that's just an assumption.