minecraft?

BL2 is great.

If you can get it to run; Daggerfall is the king of open world games.  Break into a shop at night, steal a cart, load everything in the shop into the cart, come back the next day sell the merchant back his stuff.  It is the predecessor of Skyrim & Oblivion.

Mount & Blade & M&B: Warband is similar but different.  You have open field medieval battles on horseback & on foot, an overworld map where you travel between cities & can engage bandits and other kingdoms.  Jousts & tournaments to compete in.  Damsels to woo.  You can go to cities and buy stuff, run missions, etc.  And build up your capital city & castle.  It comes with a trial but I bought it about 30 minutes into the trial after getting my ass handed too me in a tournament.  The controls are hard to get.  Stick with it on a low setting and ramp up slowly; the game is unforgiving.  Horseback archery & jousting take lots of practice.

It is pretty cool however to be on foot with a two handed sword and someone charge you with a lance and you cut the horse out from under them.  Or pick a mounted enemy off at 100 yards with a bow from horseback.

sigh, i just reinstalled it.  There goes more time i'll never get back

Currently I am playing Shadows of Mordor. This is advertised as Batman + Assassin's Creed. Since I didn't play Batman and I somehow cannot stand the AC camera turns (literally, I get nausea by its graphics, same problem in Uncharted 1-3, have those games in my sideboard, never played them for more than 10 min.) I cannot confirm this advertisement.

But I can say I never played a visually more impressive franchise than SoM. It does have its problems and I consider it to be a casual game as it can be.

Spoiler: The main story's endfights are motherfucking scripted fights with goddamn QTEs!!! That's a reason to ignore this game. If I knew that from the beginning I never bought it. But I did so I played more than 80 hours anyway  .

The combat the animations, the Orc VOs, taunts, little personalities of them are greatly done, in my opinion. The end of this game is anti climactic as it can be. So, if you like open world games and ike to murder your way to Mordor and Nurn within Peter Jackson's LoTR visuals then this game might be for you.

BUT considering the end you may want till it is less than half price. Murdering and dominating Orcs is cool and keeps you busy, but once you dominated all Orcs and succeeded in the dnfight QTEs, there is nothing more to do except DLC challenges (Trials of killing Orc cpt.s + warchiefs under special conditions). You can't use your built up army to fight vs. other players or Sauron, you just have them and collect them like virtual action figures. You can start power struggles and level them but ultimately you can't use them on a higher strategic level in this game.

It might change in 2015 but so far you are limitted. Still, I had more than 80 hours of fun with main game plus additional DLC, so for a casual interlude you might wanna check it out.

p.s.: SoM is another open world/ area with infite respawns you just kill, interaction and NPCs are scripted. Yeah, it#s just the fighting part of Skyrim I guess, everything else is simple and made for casual gaming.

Modded Morrowind ? ( immersive, just clunky combat )
Modded X3 ? ( still probably "open world", you can go wherever you want, but there's good chance you will get your arse kicked ).
I think Gothic 2 was "open world" too with some metagaming unless you wanted to get killed by 1st Orc ha.
It's been a while though.

If you have patience and a Wii U the next Zelda looks pretty open-worldly.

This one
http://www.ign.com/games/the-legend-of-zelda-hd-wii-u/wii-u-110801

Unknown release date except sometime in 2015, hence the part about patience.