The other day I picked up the enhanced editions of Baldur's Gate 1+2 and Icewind Dale during the sale to get started with all those classic CRPGs. In addition to the aforementioned I want to play Icewind Dale 2 and Neverwinter Nights 1+2.
The thing is, I haven't played an RPG in a long time because back in the day I used to obsess about stats and builds. When I played Dragon Age Origins, Fallout 3 or Morrowind I read up so much on character progression that I already knew way too much about these games before even starting to play.
I don't want to do this anymore. I just want to start up these games and delve into them. But I'd also like to be challenged so easy mode is no option.

What I want to know is: Can I just play these games without reading anything but the included manual or is it easy to spec characters in a way that makes progression impossible at some point?

Right now I started playing Pillars Of Eternity. The idea is to get into these games system that way. PoE is pretty much holding one's hand during character creation by highlighting important attributes and detailed descriptions of classes, skills and talents. But I know that Baldur's Gate doesn't really do that and that there is no option to respecs in the older games so I am a little concerned with making fundamentally wrong decisions when I come around to play those.

Baldur's Gate 1+2 and Icewind Dale, unfortunately, are poor choices to try and play without reading about stats and builds. The problem is that you have to choose your starts at the start of the game and can't improve or change them as you progress. Also, the stats aren't balanced against each other, and there's the fact that sometimes the difference between 8 and 14 in a stat is nothing. There's also the issue of weapon proficiencies, where you have to choose what weapon types you want to be good at without knowing what each weapon type is good at.

You can play it safe and simply have each of your characters stick to a specific class. And with Neverwinter nights you will also have the option to have skill points and such distributed in a 'recommended' way. Neverwinter nights does have prestige classes though, with certain prerequisites that need to be met. Those are fine to multi-class to. Personally I like the Red Dragon Disciple.

Overall I wouldn't be too worried though. Unless you multiclass in a weird way, or do dumb stuff like prioritizing intelligence for a barbarian, you should be fine. That is, along as you are familiar with the basic D&D rules for the game you're playing, like how Armour Class and Thac0 works. With a basic understanding of the combat mechanics you should be able to make reasonable choices come level-up time.

The only thing to remember with baldurs gate (d&d in general) is that fighters reign supreme up to level 10 roughly, so mages really struggle in bg1 for instance. After that they become really powerful. The characters have great flexibility, I have done bg1 with a mage, the whole.set with a couple.of varying parties, and solo'd the game several times (thief, sorceror). So it can be done with most varieties and there are companions to fill gaps if needed. You can also.spec a full 6 team in bg by selecting lan play and then setting all the characters. There are real challenges in the game, most however you can avoid if too hard. One other thing to add, if you want more of a challenge, the lookup big world for baldurs gate. It (never tried "enhanced" bg but it should work) combines bg 1&2, then adds in gigabytes of various mods which add quests, npcs, and so on and you can set it to default - just the extra content, or tactics which ups the difficulty. Oh, and a final note, if you want hard, find kangaxx!

For iwd, this is different from bg, more.combat focused, linear, less story. Its still good enough, but doesn't have the depth of bg.

Nwn, well, they are ok. Never liked them as much as the infinity engine games. Forget the main story (2 especially) as they are pretty bad, go for mask of the betrayer in 2, or have a look at the vast array of great mods.

Poe, again, was ok. Bit dumbed down, have also.solo'd around half through.

Don't forget some of the other main ones out there - planescape (more story than anything else), goldbox games (hardcore!), temple of elemental evil etc.

Read DnD v2&3 rulebooks :)
PoE isn't a good example as it is to streamlined and balanced, you can't make glass cannons there or good casters as the mob AI is retarded and it's well, as I said before, too balanced.

EDIT: added dnd version

Thank you for your detailed answers.

I just had a look at Planescape Torment and this is a perfect example of what I want to avoid. In the first part of a Let's Play on youtube I just learned that you have to max out wisdom in order to not miss a huge portion of this game's story. This is exactly what I mean. How does anyone know this without studying wikis and forums before starting to play a game?

This alone is discouraging me so badly that I don't know wether I should even try getting into these games or just stick to the current Obsidian and Larian games. PoE and Divinity Original Sin seem so much more accessible.

The thing is, even though you're trying to play the games differently this time, you're still in the mindset of a min/max player. If you want to get all the best result and don't miss out on anything at all, there's no way around reading walkthroughs and guides (and even then, it will not be possible to experience everything in just one playthrough).

If on the other hand, you just jump right into the games and go with what feels right to you, you might not always get the best results, but you'll probably manage just fine, even in the older games (especially since you're looking for a challenge). Just stop worrying. I don't remember if I occasionally checked a guide or walkthrough when I played Baldur's Gate and Planescape: Torment back in the days, but I certainly didn't study them before playing, and I beat both games (although I admit, in Baldur's Gate 1 I cheated a few times when I got bored or when facing dragons, which I think are difficult and tedious to fight even when you know what you're doing). I haven't heard of anyone failing to finish these games because they screwed up that badly, the games are usually quite forgiving, even the older ones.

If you want to play it safe, then choose a fighter as class and stick to that. That should be easy enough. (Or a caster in Torment, so you can max WIS, INT and CHA for more dialogue options, since the game is more about story than combat.) Or play the newer games. Neverwinter Nights is easy, I doubt you can really screw up in that one. (Also considering that the "recommended" ability choices are often rather lame and if you choose your own, you'll probably be a bit better than if you'd go with the recommendations.)

Actually (and this is a problem in all the games based on 3e/3.5e), if a spellcaster has a low score in the primary spellcasting stat, that character won't be able to cast spells and will therefore essentially be non-functional. For example, a Sorcerer with 9 Charisma will not be able to cast spells at all.

(I happen to dislike the "minimum ability score required to cast spells" mechanic in games where ability scores don't change much during the game.)

Well, the premise is common sense, of course. These games are not 100% fool-proof. If you consciously try to, you will find a way to screw up. But it won't happen to the average player who pays a little bit of attention to in-game infos and does everything in moderation. Setting CHA to 9 is something a min/max player would do, someone who's afraid of messing up would avoid any negative stats. Of course it helps to know basic D&D rules, but learning what the primary attributes of a give class are is not the same as reading internet guides. Even if you don't have any clue about it at all, this info can most likely be found in the manual or even in in-game descriptions.

One solution would be to pick a flexible enough role you want to play so min-maxing doesn't enter into the equation but not so rigid that you end up with non-progressive direction e.g pick full Strength for a Caster-class. As for the highlights in Pillars of Eternity I actually liked that a great deal, it made it easier to actually see what was useful and how it correlated to other information.

Just avoid guides and pick a role before you have even started or make a few weird characters you like and then pick one and stick with it. Indeed, those restrictions are completely unnecessary. These design choices is why I actually always read some basic, non-spoilers guide to RPGs because I don't want to ruin the games by overextending the time I play them pretending to experiment with builds but in reality all I'm doing is being a slave to the game's faults.

From a game design standpoint, another approach would be to make sure that all stats are meaningful for all characters. Pillars of Eternity, for example, makes it so that the equivalent of Strength also affects spell damage and healing, so everybody can benefit from a high score in that stat. There was actually a GDC talk about this sort of thing; I believe I posted a link in the Pillars of Eternity subforum. (Note that I have not actually played the game in question; I don't like real-time with pause.)

I think the idea with these kinds of RPGs, including e.g. Fallout games, is that you will replay them several times, learning from your earlier plays what you would have wanted to do maybe differently or with a different character, or simply trying the game out with several different kinds of characters.

Perhaps the meaning isn't even that you'd get all the gaming content in one playthrough. Some quests are e.g. reserved for evil characters, some quests will be available only for intelligent or charming characters, etc.

However, I have to admit I quite often check some FAQ if there is some kind of preferred kind of character with certain skills etc. to get most out of the game in one playthrough. I'd say that e.g. in Fallout games the game is more fulfilling if you have an intelligent and smart character.

The requirement put on a game designer would be too high. I mean, won't that cause weird balance issues? Anyway, I didn't play Pillars of Eternity for long so I don't know how that really worked, I also only created 1 character.

Definitely but that makes RPGs even worse time sinks than they already are. I wouldn't mind replaying Arcanum as a stupid, anti-social character. Problem is I would have to make sure that I give him or her some basic skill that will make combat doable not to mention the needed time.

It's a pity we get so many games but our limited time stays the same or its limitations even increase as we grow older (excluding retirement).

Yes, this I like very much about PoE. It makes my Druid really fun to play because Might boosts both my magic damage and my melee damage in animal form. That is actually another thing I am trying to do: Playing different classes than the same human fighter I have so far played in ever RPG in my life.