I haven’t played any Baldur’s Gate games before but I’ve heard so much about this game that I’m going to buy it.
However, before I start, I always wonder about this: some games allow you to unlock any weapon at some point in the game, and if you miss one in some quest you can always go back. If you accidentally sell one you can buy it back or forge a new one again, or have it respawn. If you want some other class you can switch later.
Other games are not like that, and if you screw up or aren’t aware of [full in the blank] then you can’t unlock something.
What’s the story with BG3? Do I need to be careful and plan before going on missions?
Keep in mind, while this is a video game, it’s based off Dungeons & Dragons 5e. Many choices have lasting effects.
tl;dr Don’t approach this game as a traditional action RPG game. Treat it like it’s the table top game you’d play with people with one person (the DM) weaving a story for you based on what you do in your adventure. Or like a choose your own adventure book and you didn’t take your figure off the page you came from…
Far as I can tell, there’s no respawns. You do not grind gear/experience. If you avoid doing stuff you are by nature, less experienced then someone who does more. Quests can be resolved because of actions you take that don’t directly relate to the quest. Example (without being a spoiler), you are tasked with rescuing someone… but decide you’re going to pack it in for the night instead of addressing the problem right away and that person dies. The quest is resolved. Not all quests must be resolved one way, many have multiple options and outcomes based on what you choose to do or not do.
You can also lose access to certain vendors. But you can also gain access to better vendors. (Or you could rob the vendor, or murder them and take everything). But at the same time, you don’t need to be as focused on gear than you would other games. Gear is more about additional options. The shields you find at the very beginning of the game, have the exact same AC as those at the end of Act 1 (+2). Wouldn’t surprise me if the ‘best’ shield only has +4 AC. But the shield might have active or passive abilities and that’s more so why you’d want it. It’s not like say… Diablo were you absolutely wouldn’t think of using a starting weapon later. But in DnD, the damage you do is based on what dice gets rolled for it (say a d8 or a d10) + your modifier + any enhancements it might have. But an end game swords base damage (excluding say, special effects) would hit just as hard as a starting sword. But maybe your build lets you swing that sword more than once… maybe you took a warrior/warlock build and someone hasted you…
It’s a game where choice matters. Dialog options matter (some in the short term, some long term). Go up to a random drow and tell her “fuck you and the horse you road in on” don’t be shocked a fight breaks out. Tell a devout follower that their god is weak and stupid, they might attack you. Try to fake drinking something only to fail the dice roll and you might get jumped by a large number of enemies who no longer trust you unless you can talk your way out of it.
Hell, even doing events in different orders can change events and options.
So you’re not going to see/get everything on your first play through. And that’s fine because it’s going to spark your imagination for next play through. Example, I’ve seen a lot of gear that empowers you with lightning… and gear that makes me immune to being electrocuted, and boots that electrify the ground if the ground is wet. Right now I’m a smiting paladin, but maybe my next playthrough I play a monk who’s just got an electric personality…
Just to further illustrate your point to OP, I’m deep into Act 3, nearing the end of the game, and I’ve found a single +3 AC shield in the entire game. Even the super late game bosses drop a shield with the standard +2 AC and some unique and powerful effect, rather than a “better shield”.
Yes, there are unique weapons you can miss out on. None of them are so unique or powerful that your experience will suffer greatly because you missed it. In one case, a side quest allows you to craft 2 of like 7 potential pieces of equipment and doesn’t give you enough material to craft any more. That’s the nature of the game: you have to make decisions and work with what you find. On the plus, this makes sharing the experience with friends and playing the game multiple times a substantially better experience.