The points at which the game transition between acts seem a bit arbitrary (mainly for Act I to Act II), and I don't see a narrative or mechanical reason to lock us out of previous maps and quests. As far as I remember, previous Baldur's Gate games didn't have this kind of points of no return. Why do you think they did it? Do you like it?
There isn't a point of no return between A1 and A2. Rather, you need to do certain A1 events prior to A2 or those events resolve without you (e.g. Goblin Attack, several others).
You can travel back to A1 while in A2. Only A3 prevents back-travel, and that's for well-established story reasons.
I generally prefer having control of the timing rather than having it being tied to X amount of rests or something (notable exceptions for certain quests existing, of course).
BG2 and ToB both had notable points of no return. Paying the fee in Athkatla to recruit allies is one, any time you ever travel with Saemon is one, leaving the besieged city is one in TOB, etc. There were also a number of time-dependent quests, most notably those involving a certain dragon/drow situation.
It's when you go to Nightsong that it locks you out, and to be fair, the game does clearly warn you there are consequences for that - and depending on your actions, a 3rd party just straight up moves the story along, so it makes sense.
If you're struggling at the forge, remember that you can just not hit the boss with anyone but a bait character, and that bait character doesn't have to actually survive the encounter, meaning if you position well, you can just melt and smash the boss over and over without touching it (after the first hit or two) and it's a free win.
You can still travel between act 2 and act 1, I think the quests are locked out because the NPCs involved have moved on to the new area. It’s a little annoying to be unable to finish some things up but I don’t really mind overall. It’s nice that the side characters make some progress in the story.
The only point of no return I encountered was once you head into Baldur's Gate itself, you can't go back to any previous area. All the other areas before that may give you a vague warning implying you can't go back, but you most certainly can. Though at some points, the only way back is to fast travel, since you can't just turn around and go back the way you came because you had to jump/fall into a pit or something.
I do find that one point of no return silly. The only logical reason I can think of is that they didn't make an uncursed version of the woods, so it would be immersion breaking to go back there. But plot wise? Shit doesn't make sense at all. There's no reason I shouldn't be able to go back to Emerald Grove once I reach Rivington.
Yes, I found it confusing that sometimes there is a warning which has no consequences, then in anothere you get locked from all previous maps. Also with time-sensitive missions, you can fail a few quests and it is not always specified that there will be consequences if you take too long in your exploration (in a game that is all about exploration)
In act 1, if you don't resolve the druid/goblin/tiefling dispute, and iirc the burning house before reaching act 2, it resolves itself. If you did nothing the grove's ritual finishes, if you killed the druids the goblins invade and kill everyone, and the other options don't matter since you would resolve the quest, oh and karlach's personal quest too, if you don't do it she leaves.
Odd, I tried to go back to Act 1 from Act 2 (looking for a vendor since spoiler stuff happened at the only settlement in cursed lands) and when I clicked the elevator it told me I "really shouldn't" like twice and the third time it game over'd me in a unique and creative way... I felt that was a pretty hard lock out of act 1... Lol
I think there is a grace period after hitting act 2 where you still can go back but once you've done a bit of story related stuff you are pretty locked in.
You could try just opening the map and bringing up the list of fast travel spots. This will let you fast travel even to points on another map. Like if you're in the under dark, you can warp straight to Emerald Grove without going back up topside. I had to do this when in the basement of Moonrise Towers because I wanted to go back and sell shit before moving forward, but there's no transition back the way you entered.
I think the problem is you're viewing it like you would say Diablo. Where those have acts and you can just freely roam through the whole thing.
This is d&d. So this is more of a linear story. More precise your linear story. If your story involves going from the beach to baldur's gate and you never saw the underdark then that's perfectly fine. There's really no right or wrong way to play.
And that's where the massive amount of replayability comes. Because long as you don't keep choosing the exact same things every time you will get a different story.
The problem with this is the encounters and enemies have specific levels. If you skip things (and there are several instances where progressing one quest ends or eliminates many others even when they are not mutually exclusive, a la evil vs. good companions) you could end up very underleveled later on. I had several fights early in Act 2 where I felt I was VERY obviously missing content as I needed my entire party to be a level or two higher to get through without save-scumming, spamming items, exploiting mechanics, or all of the above.
A lot are super not obvious too - in Act 1 there are quite a few things you're "supposed" to do before you go to the goblin camp or else you'll be pretty unprepared to deal with the sheer number of level 3~4 mobs. But I assumed initially it worked like more traditional RPGs and you do the side quests first and the main quest as the last thing before wrapping up the act. You can also sneak around and pretty much get instantly TPK'd by the Spectator until you have the action economy to deal with it (level 5ish). But in Act 2 you're actually "supposed" to go to Moonrise first before going to the Mausoleum or else you lose the ability to finish tons of quests and access to several vendors. You're told to find tieflings, Mol, and Zevlor all at the same time but you have no way of knowing that if you go to the mausoleum first you'll lose access to the tiefling quest resolution, but not the other two. It's not obvious at all that you can't find Mol until Act 3. It's missing the kind of corrections and hints a DM could do on the fly to keep things moving, or at least nudge you in the right direction if you're willing to be railroaded in order to see the most content possible.
Iirc you don't lose access to anything in the mausoleum until you take a dip in the pool, where they quite literally show a popup that uncompleted quests may be broken. If by that point you check the map and the quest log and you have stuff you clearly should do before continuing, like exploring the tower, or freeing th eprisoners they will obviously murder if an assault happens to avoid having to fight them in the case we liberate them in the assault, well, yeah, idk man.
My only gripe is the Zevlor quest and the Mol quests, where the don't really say that you need to do it to see them. Well technically you can go down below through a hole and featherfall or through some stairs after liberating the prisoners, and rescue Zevlor before the pool, but most do it after it. SO my only gripe is Mol, because the journal gives no indication that spoilers of act 2:
spoiler
she was not at the towers
But besides that it's quite clear that once you reach the gauntlet that maybe that's a bigger thing than a simple side quest, specially when the popup shows up.
The game warns you before you enter the mausoleum. There is even a character who warns you. That's exactly how a dm would do. You even have 2 warnings actually. One when you enter the mausoleum, and one when you enter the final zone of it.
I feel like level is a bit less important than people think, at least for BG3.
Lower level simply means less HP and fewer spells to work with. But your damage for the most part doesn't change (except for like lvl 5 as an example). In this video, this guy solos Act 1. It does require more planning and tactics. But if you can solo this stuff, you certainly can do it with fewer levels. Just those additional levels will make it easier.
What do you mean? If you enter Act 2 from the mountain pass, that probably breaks some Grymforge quests, but the underdark is very much still accessible.
So long as you don't progress past the Mountain Pass into the Shadowlands you can go back and do the Underdark no issue, and you can still go back and hit the underdark even after that (all the way until Act 3) though you will miss some quests that way.
I'm waiting for a mod to allow the back travel for my second play through, also hoping the level 20 mod gets updated to allow you to level your main class past 12