It’s counted as a separate game from Elden Ring proper rather than another DLC part of the main game. The thing is that, the intention is built for 3 players rather than solo: but can it be played singleplayer or not? Besides that, are there any differences between this game and actual Elden Ring (apart from the UI)?
I love all Fromsoft games but Nightreign has become my favorite. To me, the roguelite angle ‘solves’ a lot of the small issues that arpgs have. I could go on and on but there is already a lot of info out there.
All I’d recommend is to definitely play three-player runs, even with randos if you have to. That’s the best way to learn pathing and other important strategies. Of course there are plenty of shits out there but the vast majority of co-op experiences I have had in Nightreign have been great.