Can someone explain what you do for fun in this game outside of the main story?
Basically just explore and come across things (gigs, police gigs, random altercations, random secrets, of which there are
tons dotted around
everywhere).
The game fails to be an RPG because it has no particular form of progression (e.g. fixers, factions, etc.) or sense of achievement (other than the intrinsic satisfaction of discovery/completionism) attached to doing that, but if you enjoy the combat, then in terms of moment-to-moment gameplay loop satisfaction, it's alright. And even random little altercations usually have a flavour shard left on the scene, telling of some gangoon betrayal or some horrible bit of human trafficking or whatever, none of which are necessarily stellar bits of writing in and of themselves (though some actually are good), but the accumulation of which builds up a good background sense of the world's hopelessness. Also, there are a bazillion amusing passing conversations that NPCs have that you can chance upon. It's not as fleshed-out as it could have been, and should have been, but it's certainly not completely shallow either.
Another thing I've noticed (this being my third "proper" time pootling about in the game, actually progressing a character): the day/night cycle means that the "set encounters" can feel quite different. There have been several occasions when I've done a little random scenario and suddenly realized, "Oh yeah, this was the same as
that memorable encounter on my last playthrough". Case in point: there's a shard trail that reveals there's a guy needing to escape the vengeance of a gang, and his sis tells him to meet up by the waterfront where she's got a boat or something, but the gang catches up with him at the rendezvous point, and they're hanging around in the aftermath. On one playthrough, I followed the trail to the rendezvous point from a clue in a shard in a previous encounter, and came across it by day, actually trying to see if I could help the guy. On this playthrough, I came across it just in the course of wandering about at night, and didn't realize it was
that scenario till I read a shard on his body. The encounter felt
totally different just on account of the different psychological context and day/night difference. (There are actually quite a few small "interconnected shard stories" that aren't even flagged as missions, you just find them if you follow your nose.)
Also, Night City is just vast. I keep thinking, "Hmm, I'm going to really start recognizing the whole city's pattern and it's going to get boring wandering around because I'll have seen everything and know it all." But while I'm certainly recognizing little chunks here and there, I keep coming at them from different angles, and the whole thing still isn't really joined-up in my mind, so it still feels even bigger and more mysterious than it actually is.
The game really takes advantage of, and uses well that syndrome where you get used to the familiar "aspect" of a place from one angle (e.g. an intersection where you live), and when you come at it from another angle, it has a fresh "aspect." IOW, the city is big enough for a game, but it
feels even bigger because of this aspect of the design (from the knotty intertwining of the streets, alleys, etc.).
A lot of it depends on how susceptible you are to getting immersed from an accumulation of background detail, which gives you a sense of the world you're in that you then bring to encounters. It works pretty well for me in that sense.
I should add: when people talk about replayability in a CRPG, I've never found them particularly replayable on the whole, only from the point of view of trying out different builds. But this is perhaps the most replayable game I've ever played. Which is extremely paradoxical because in its backbone it's also one of the most linear, story-driven games I've every played. But it's because of Night City itself being as above described. Because it's a giant sandbox that you can just wander around and have fun in (again, if you enjoy the various forms of combat, which I do) - it actually
functions as highly replayable for me.
*sigh* That fact makes one wistful about what could have been - if it had had lifepaths, fixer progression, faction progression, etc., and the sandbox had a bit more structure and if you could have built actual sandcastles in it, it would have been amazing. But even as it is, it's still good, light-hearted fun.