Morrowind/Skyrim (Liked Oblivion far less than the other two, but still enjoyed it), Fallout 3/NV, Watch Dogs, Assassin's Creed 4, Sleeping Dogs, All the GTA games. I played a little Saints Row, but not much. What little I did play I enjoyed though.

1. Sleeping Dogs
2. Assassin's Creed: Brotherhood
3. Batman: Arkham City
4. Far Cry 3
5. Tomb Raider (2013)

Arcanum, by far, followed by arma/operation_flashpoint with friends.

A toss-up between New Vegas and San Andreas.

Fallout 2

DayZ and Eve Online

1. Sleeping dogs
2. Far cry 3
3. Fallout new vegas
4. Fallout 3
5. Assassins creed 2
6. Ni no kuni

mmm...

Gothic 3

Fallout 3

Far Cry 3

1. S.T.A.L.K.E.R. - Shadow Of Chernobyl
2. S.T.A.L.K.E.R. - Call Of Pripyat
3. S.T.A.L.K.E.R. - Clear Sky

1) Elder Scrolls Series (doesn't include the Online game, though. I hate that thing. Paid way too much for way too little)
2) Saints Row Series
3) Fable: The Lost Chapters
4) Need For Speed: Rivals
5) Need For Speed: Most Wanted

Mafia 2

1. Just Cause 2

2. GTA: Vice City

3. Gothic 3

4. Morrowind

1.Fallout 3

2.Just Cause 2

3.Sleaping Dogs

4.San Andreas

Pac-Man

1. red dead redemption

2. grand theft auto 5

3. the elder scrolls oblivion

4. saints row 1 and 2

5. grand theft auto san andreas

1) Ultimate Spiderman

2) inFAMOUS 2 (I haven't played Second Son so this could change in the future)

3) Elder Scrolls V Skyrim

4) Borderlands 2

5) Batman Arkham City

Honorable Mentions: Assassin's Creed Brotherhood, Dark Souls, Fallout New Vegas

When February 2015 comes around one of these titles will be bumped off the list to make room for the Witcher 3 Wild Hunt. (It will be Batman)

1) The Elder Scrolls Series

1) Skyrim
2) Morrowind
3) Oblivion
4) Daggerfall
5) Arena

2) The Fallout Series

1) Fallout 3
2) Fallout: New Vegas
3) Fallout 2
4) Fallout

3) The Grand Theft Auto Series

1) Grand Theft Auto V
2) Grand Theft Auto: San Andreas
3) Grand Theft Auto III
4) Grand Theft Auto IV
5) Grand Theft Auto: Vice City

4) Sleeping Dogs
5) Watch Dogs

1. Far Cry 3
2. Watch Dogs
3. Sleeping Dogs
4. GTA San Andreas
5. Mafia II

Factorio (I uno if it fits but is still open world)

Dead Rising 2: Off the Record

Cube World ( I don't care what people say even in it's state lots of fun)

ARMA 3

Far Cry 3: Blood Dragon (due to dragons)

Kinda an odd one The Escapists linky (will be on steam next week)

Also for fun. . . I love Space Engineers (but space soo)

I'm also kinda hoping Planet Explorers gets less buggy but 'm enjoying it too

1. just cause 2

2. skyrim

3. mount and blade: warband

also Stalker, SR, GTA, Far Cry, mafia...

Gta san andreas haha :D

JUST CAUSE 2!

Skyrim

GTA 5 hands down best ATM cough watch dogs could learn a thing or 2

The Elder Scrolls Oblivion is with mods the best :D