Is this game viable to solo? I started a solo game w/ fighter and I haven't had much trouble through the beginning except for the ogre in the cave where the caravan was ambushed. I hit level 5 in the beginning area and now I'm on my way to the second city.

You may have some issues later on, but it can definitely be done. People have done it with various builds. Personally, I'd go with a dual class character. Likely FTR/Mage or maybe Thief/FTR.

if you are referring to IWD1, then i would say yes, it is solo-able and I recommend a combination that includes thief, since this will help you a lot when it comes to dealing with traps and locks. having some caster power is very nice as well.
writing this gave me an idea; next time I play IWD1, I am going to try and solo it with a cleric/thief.
if you make a (fighter/)wizard/thief, you will be able to use invisibility to repeatedly inflict backstaps for rather awesome damage.

IWD2 solo is most easily done with a caster type, be it wizard, druid or cleric.

There's doable and there's fun.

I started off IWD1 in solo (fighter-thief). All I was doing was either kiting mobs with ranged attacks, or bottlenecking hordes into doorways not to be surrounded.

After some multiplayer, I realized how dull an approach it was. First I expanded to 3 toons, then 6. Immensively more fun not just for the added abilities, but for the tactical micromanagent.

It went from a dull action game, to a combat rpg.

I personally find 3 or 4 characters is the sweet spot. You get enough spells and abilities to give you a bit of a challenge and you still get that tactical combat. 6 characters is fun too, but I tend to find my spellchuckers are just relegated to an archery role and/or the occasional buff most of the time when I have that many characters.

I attempted a solo paladin. Never had trouble with traps/locks (str 18 + holy might = str 26, plenty for bashing any lock) but got bored for the same reasons that xdiesp above was referring to.

It was challenging all right, the whole way through, but after I hit level 30 about halfway thru the game (was on hard difficulty) and was still using the same "rest, buff, lead enemies to choke point, kill 3, run away, rest, repeat" strategy it got pretty boring, and considering the game is thin on story to begin with, it just wasn't worth continuing. In particular, killing Ixunomei's High Summoner after he had created a nightmarish clown-car-of-trolls scenario was just painful. It took literally four days, 5hrs/day of gameplay to untangle that mess.

I recommend against solo because (1) it's boring and (2) it never gets very interesting esp. considering unlike BG2 the other characters in the story don't even comment on you being alone, (3) there are no helpful items for solo characters, and (4) it just doesn't work as an "action game" once there are no more levels to gain.

I agree 3 characters is the sweet spot, ESPECIALLY if you download the NPC mod, which is awesome despite dubious voice acting and a poor translation from Russian. It VASTLY improves the game to be able to chat/flirt with even just 2 party members of your choice once in a while.

Plus a 3-man group retains the fun "multi-tasking" aspect you get from soloing (ie you depend on everyone to have, melee atk, range atk, use items, sneak attack, and cast spells), and yet it keeps the difficulty up. Plus, on "Hard" mode I think that you will all be at l30 by the end (I am halfway through and now and me, Teri, and Nella are all at l15).

In icewind dale 2, I got a solo cleric5/rogue2 done with the main battles in chapter 1 and up to the orc fortress i lost interest. It was tough at times, but it was fun. Clerics are good with undead summons in iwd2 and rogues are good at sneak attacking and stealth. With summoning and stealth combined, talking about a nasty combination. Definitely should be able to solo.

I soloed it with a dual-classed human fighter-mage (dualled at lvl 6), also at hard difficulty. The higher difficulty doubles all experience gained. So just by completing all the quests in Easthaven, you should be able to get to lvl 5 by using a single character. By the time I got to Kuldahar, I was lvl 6 fighter and ready to change class to mage.

The problem with a mage as a solo character choice was that by the time you get to the Dragon's Eye, you will level up faster than you can find spells to fill the higher slots. You won't see lvl 6 spells in the game till the Severed Hand, nor lvl 7 or higher till Lower Dorn's Deep, yet you will have many unfilled slots for lvl 9 spells easily by then.

So in short, once you have completed Dragon's Eye solo, you might as well create a second character to share some of the insane experience (most monsters in Severed Hand give 1500+ exp per kill). I created a new dual-classed human fighter-cleric at the start of Dorns Deep, and leveled her up to 6/7 in about 5 minutes, with my main character doing all the fighting. By the time we made it to Lower Dorn's Deep, she was 6/20 and could auto-smite all undead just by standing still in the room.

Imo Paladin was a poor choice to solo because it's your combat magic which is the most deadly killer of massed monsters rather than your melee prowess. Paladin does get spells, but too little too late.

As a fighter-mage, the Armor spell was quite handy so I could cast freely, although equipping armor and taking it off while you cast spells is also viable (gamey pause button abuse, but it works). My standard spell buffs were Mirror Image, Speed, Protection from Evil, Improved Invisibility. Then walk straight through a group of mobs to aggro as many as possible, run quickly to the side and cast Web/Confusion so most tend to collect in one area, then use multiple Fireballs to kill them all en-masse. If you encounter spellcasters, just hit them with an arrow to disrupt their spells and they are no problem. If you encounter fire-resistant monsters, just switch to cold-based spells and do the same thing.