Not exactly a sequel, but more a remake:
Legends of Nosgoth, the Complete Story

A single game with all the story, no fillers, a definitive ending, less backtracking and repetition, only the good gameplay, enhanced graphic.

It will never happen :' )

Ah, and I agree about a TLJ2 real sequel.

Oh, Anachronox 2...I knew I was forgetting something really obvious!

Nocturne 2 (by ex-Terminal Reality team funded by Take Two and with assistance from Rockstar)
Duke Nukem 5 (with George Brussard as co-executive and $50 million budget)
Blake Stone 3 (made on Unreal Engine 4)
God Of War 4 (with Gods from Norse Mythology)
The Legend of Kyrandia 4 (by ex-Westwood)
Little Big Adventure 3 (by ex-Adeline Software)
Goblins 5 (by Pierre Gilhodes & ex-Coktel Vision)
System Shock 3 (by ex-Irrational Games & ex-Looking Glass Studious)
Myth 4 (by Bungie Studious)
Thief 4 (as a continuation for Thief 3 with hard & sometimes long lock-piking mechanics, super light & shadow engine maps, different ways to steal things, more mystical magic and undead things, big castles, waking up soldiers after knockout, more secrecy machinations and behind-the-scene schemes and involvement of Keepers Order)
Disciples 4

A true sequel to the 3d era mechanisms and gameplay Grand Theft Auto series, is my long yearned dream... After San Andreas, each and every game they release (4, expansions and V) seem total crap to me... Of course, counting the bugs, the instigated "realism" and the craptastic DRM out; with them, i consider them rock bottom. Plus they miss lots of features the 3d era games had.

Streets of Rage badly need a sequel, as well as Golden Axe. Seeing with Igavania that old style of games is still in high demand and people gladly pay for such games, it is both a pity and a waste to not have one, at least as an official, high budget, professional work release. Even though SOR Remake was better to even a professional work...

A true diablo 3 wouldn't hurt, either. Not this crap out there. Probably the ditched pre alpha version would do it, for me, if it was worked upon and finalized.

1.) Little Big Adventure 3

2.) Monkey Island 3 - this time by Ron Gilbert

3.) Bioforge 2 (was planned, sadly canceled)

Well for starters one that will never happen but here it goes => Real Fallout sequel and I don't mean Bethesda infested FPS Non-RPG Non-Fallout sequels!

And then:

KotOR 3 => from Obsidian since BioWare is gone, they are gone!
Full Throttle 2 or episodes at least from TellTale
Half Life 2 Ep. 3 or Half Life 3 => probably not gona happen
Jedi Knight 4 I think since 3 is Jedi Academy
Vampire The Masquerade sequel, number 3 I presume


And finally Star Control sequel, a real one from geniuses Paul Reiche III and Fred Ford from Toys for Bob!

Baldur Gate 3
Icewind Dale 3
Wizardry 9
FF Tactics 2
Tactics Ogre/Ogre battle next chapter
Fallout 3 (by Interplay)

quick note: added some of the games from the comments which i like also and would love to see them
seems like i oscillate on that lucky number 3 again :)

System Shock 3, just because the second ended on a cliffhanger.

Space Quest 6.

FTL 2 could be great, the devs don't seem interested though.

A proper Hitman, not that weird stuff they announced at E3. :P

And Dawn of War 3. But a proper successor, not that weird stuff that Dawn of War 2 was. :P

A new Blood Omen or Soul Reaver. But proper sequels, not that weird stuff that Blood Omen 2 was or Nosgoth is. :P

Darksiders 3. But a proper follow-up to Darksiders 1, not that weird stuff that Darksiders 2 was. :P

A new Command & Conquer. But one that stays true to the original's spirit, modern real-world + sci-fi, not that shoddy post apocalyptic stuff that the later Tiberium games were. :P

Beyond Good & Evil 2. Just friggin' Beyond Good & Evil 2. :P
The last game in the series was Space Quest 6. I believe you meant to say Space Quest 7.

No I did not... maybe there should be a thread of "sequels you ignore."

Color me confused, by why on Earth is the OP low rated on this?

According to your subjective opinion. Let the man want what he wants. :P

Still possible:

 ▪  Beyond Good & Evil 2
 ▪  Remember Me 2
 ▪  Alan Wake 2
 
 
Unlikely to happen:

 ▪  No One Lives Forever 3
 ▪  SWAT 5
 ▪  ObsCure 3

Heh, I always enjoyed Space Quest 6 a lot, admittedly it was the first Space Quest I ever played, though. :P