I just realized that there is an original trilogy of games from 1985, as well as the newer trilogy with the same name. And a part 4 on top of that! What is the difference between these? Is the second trilogy a remake of the original, or are they completely different games? Is part 4 a sequel to the newer trilogy or the original?

Thanks!

Thanks so much for the answer! Sorry it took me four months to reply! I never realized there was a response! I don't get email notifications about responses I guess!

So the 2004 game has nothing to do with the Bard's Tale trilogy, then? Good to know!

The remastered trilogy offers three options to transfer parties between games (full power, adapted power, complete reset). How was that in the original trilogy I wonder?

In the original trilogy, the only transfer option was the equivalent of full power. However:
* Some items would not transfer between games. This is especially significant when transferring from BT1 to one of the others, but there are still some items that don't transfer from BT2 to BT3 (mostly quest items).
* Some items have different properties. For example, a character might lose the ability to equip an item between games. For example, A Wizard can use the Spectre Snare in BT1, but not BT2. (Note that, in the Apple 2GS transfer program, a Wizard transferred with that weapon will still have it equipped, but will lose the ability to equip it if it's traded or you change them into an Archmage.)
* The transfer to BT3 will cap level at 35, though other stats will be preserved. In the DOS version, XP is retained, which causes problems due to the XP table being different (all classes take 400k past level 13 in BT3, while it varies in BT1 and BT2 with most non-casters only needing 200k per level). In theory, you could fix this by being level drained in BT3, but unfortunately a bug prevents you from being level drained. (BT3 DOS is actually very buggy and should be avoided; I hear BT3 Amiga has issues as well.)
* BT1 and BT2 classic assume all your characters are male. (In an interview, Rebecca Heineman quoted Michael Cranford as saying that "girls don't play these games" (a claim I can assure you is false).) BT3 has a gender selection. The DOS transfer program lets you choose the gender of transferred characters, while the Commodore 64 transfer program (which does adjust XP to a sensible value) does not.
* The DOS transfer program lets you transfer monsters from BT2 to BT3, but they lose their attacks and will do nothing but cast Mage Flame every round. (By the way, BT3 classic has an enemy that uses this spell; I don't know if the enemy still does that in the remaster, but it honestly feels like a bug (Mage Flame is spell number 0).)

Thank You yet again!
Full power transfer probably leaves one somewhat overpowered I guess, but if that's how the original had it I could consider that an option in good conscience. As You may have guessed already my question was asked in regards to solo'ing of course: If I end up grinding up characters to ridiculous levels I may not fancy doing that all over for every game after all ;)

That said You already answered the solo question, so I'll see what I make of those complications regarding a solo. At least the full power option may be of help ^^

Bard's Tale 3 actually intends you to use transferred characters; otherwise, the early part of the game can be a slog (though I have done it multiple times).

(Then again, as I mentioned soloing BT3 is not an option, so make sure you have a decent size party with the classes I mention when you go to play BT3.)