Megaman Legends 2 *cough cough* Half-Life 2 Episode 2 *cough cough* All kidding aside, the game I would elect as "needing a sequel" would be Starbound itself. I know it's a little early for that - but I feel that the story falls short on many aspects. It was basically the lore equivalent of a tech demo to me - just enough material to make a game, with proper exposition to each elements, but quite shallow in it's value. There's so much that could be done with the timeline - both before and after the events of Starbound. That, and Bastion. Bastion would be lovely with a sequel.
Sadly, they made Transistor instead of Bastion 2. No offense against Transistor, but eh, I preferred Bastion.
I didn't mean INSTEAD of Transistor. Transistor is very close to my heart - I in fact love it better than Bastion. But Bastion comes in close second, and while Transistor was better IMO, the ending tied things up nicely. Bastion, though - Bastion left a lot of questions open, hence why I would want a sequel.
That's an oipinion that i have never seen before. Imo, that would serve better as a Satarbound expansion/DLC/B.I.G. patch, maybe like Pillars of Eternity's "The White March"
Meh, WoW. I think they ruined WoW during Warlords. I quit a year and a half ago and I have zero plans of ever touching it again.
Someone mentioned already MegaMan Legends 2, so I'm gonna add MegaMan X8. It ended on such a sequel-baity cliffhanger, and it's been, what, 12 years? We really need Legends 3 and X9, but good luck with that... One can dream, though (and wait for MMX: Corrupted to come out one day).
The Medal of Honor series needs another sequel. It was COD before COD, and it was a lot of fun. I had Rising Sun.