Yes, it's RPG and it's a standard fantasy-medieval setting with a few sci-fi elements

Might and Magic 7, golem collection.

It came to my mind when you mentioned body parts, but I dismissed it because building the golem is in no way crucial and hardly something that has to be done quickly. Plus, I was under the impression it's an adventure.

The sci-fi elements reminded me of it again. And now I understand what you mean about having to do it quickly. Building the golem has a nice side effect. "Promotion" and all that. 4 mages in your party? Or 3 mages + cleric?

4 elven female sorceresses :D I've made a similar playthrough years ago choosing the dark side but now I want to choose light side. At that point of the game it's rather difficult, my ladies die fast but it's doable.

EDIT: your turn obviously :D

I can't think of anything at the moment, so anyone please feel free to take my turn.

To keep things going:

It started pretty badly as I found a body of a friend. Sorry pal for not paying any respect to your body but I had to do it, this way it would be possible to find out what had happened to you!

A train ;)

Good, so it's probably the game I was thinking of. Now to remember its name... (-_-)

Update: Ha! Got it! The Last Express.

Of course! Great game

Your turn

Thank you.

"You know, brother, life's a funny thing: one moment you're struggling to prove that someone dear to you was falsely accused - and the next you have to fight him. I came out victorious, but it didn't go that well for me; I ended up powerless and with one of my old acquaintances dead. What do I have left? Despair... and my faithful blades."

This sounds maddeningly familiar, but I can't pinpoint it. To help narrow things down, is the game on GOG?

Yes.
I have it both in my Steam and GOG libraries.

Could you tell something about the genre and settings?

EDIT: and a wild guess: Dust: An Elysian Tail?

Darksiders II.

Yep. :-)
Your turn.