Excluding Bethesda games.

I remember NOT playing the main Morrowind storyline for a year or so. I was just wandering around the world, doing a bunch of stuff.

When I started the campaign, I was already at level 14-15. Game was too easy after that :P

I'm looking for games that I can just wander around when I'm bored and don't feel like playing anything, but have nothing to do (like before going to sleep).

The GTA games, if you've completed them 100%, you're really left with nothing to do, which is not the case with Morrowind.

Oblivion I disliked immensely, and Fallout: New Vegas was interesting but a bit empty. Anyway, I'm open to recommendations.

Edit:
Here's a list for all the recommendations in this thread for games that allow sandbox exploration:

Assassin's Creed series
Boiling Point
Darklands
Divinity 2
Dying Light
Fable series
Fallout series
Gothic series
GTA series
Kenshi
Kingdoms of Amalur: Reckoning
Minecraft
Mount & Blade series
No Man's Sky
Omikron: The Nomad Soul
Postal 2
Red Dead Redemption 1 & 2
Risen
Star Citizen
The Elder Scrolls series
The Precursors
The Witcher 3
Two Worlds 2
Ultima Underworld series
White Gold: War in Paradise
Wizards & Warriors

Gothic 1 and 2, you can wander around in them alright since they are open world and best part is, they are not as easy as Elder Scrolls or modern Fallout, also damn good games in their own right.

Thanks, I'll check them out.

https://forum.worldofplayers.de/forum/threads/1533915-RETURNING-v2-0-Stand-Fragen-Antworten-25

You could also give a try to Risen games, they're not 100% open world-like, but I remember wandering around and doing stuff for a while, and then retake the proper main story

Added to mental list!

Two Worlds 2 I guess. The first one was basically unplayable though. The second one didn't exactly grab me, but if you just want an open world to wander and do random stuff in I think it's ok.

I haven't played it, so I'm not really sure, but what about Kenshi? It seems a very solid sandbox game.

Daggerfall Unity!

This

or

Definitely THIS!

or even

This

Even though David Bowies dead and it's all sad and that you HAVE to try This

SkyDaggerOblivioWind. A great mod that has been 20 years in the making. In fact, it will only take another 10 years for the mod devs to finally give up on it.

Thanks for all your great suggestions! Now I have to choose the first one I'll try, so YouTube here I come.

P.S. Waiting for Daggerfall Unity for a long time now!

Here we go look

Daggerfall OG

Maybe they should stick with transferring the basic landmass, and maybe 10-20% of the game over, then let modders add more content and extend the game naturally with it's own lore rather than trying to move the game(s) over 100%.