Well, every series started with one game. I don't know if the W101 will ever get a sequel, but Captain Toad might get one, even if it's limited for the handheld market.

Yeah, if that happens I include it, like I will do for Watchdogs and Destiny which probably also get sequels.

I added Gunman Clive, Ragnarok Odyssey and Soul Sacrifice. The two last ones are a bit difficult, as the second game is an expansion of the first one, like Monster Hunter Ultimate. But as the additions are significant I thought it might qualify. Not completely sure of it though.

gravity rush. tearaway maybe if you count unfolded as different enough.

Is there a second Gravity Rush?

Unfolded maybe. As I wrote I'm unsure about Ragnarok Odyssey Ace and SoulSacrifice Delta, but they seem pretty substantial additions to the original game. I have no idea about Unfolded. Can you say how much is added?

it was announced at TGS 2013 i think.   it's been a while since we've had an update so at this point most playstation fans are assuming it is being ported to ps4 but it should still be coming.  seeing as you included bravery default i would think gravity rush would get the same treatment.

unfolded would seem to play  quite differntly,.. a pretty substantial change in gameplay controls i mean.  it has  new areas too,.. i think it's suppose to be around 25% more content if i remember reading right.   here's the psblog write up if that helps you decide: http://blog.us.playstation.com/2014/08/12/tearaway-unfolded-coming-to-ps4/

which speaking of,.. guacamelee and retro city rampage at least started on vita.  it was quickly ported to other systems but it started on vita.  the retro city DX and guacamelee super turbo champion edition are both quite substantial expansions on the original content. 

Sorry, missed your post, my VG-Chartz buddy was full with other threads. Anyways, I greyed out the ones were the second game isn't released yet, as it should be the case. I thought that the japanese release had already happened for Bravely Second and Puzzle&Dragons Mario Edition, but that happens in April. Same for Tearaway, Unfolded isn't released yet. Gravity Rush is a announcement without a proper date yet, so I will not take it in the list until it is more substantial, sorry.

As I wrote, I'm pretty unsure about Ragnarok Odyssey Ace and Soul Sacrifice Delta being new games, despite a lot of content. But if I go that road, Guacamelee and Retro City also qualify. I thought Retro City was first released only on last gen consoles, but Vita was there as a release-platform from the beginning.

What about the SteamWorld series? Heist isn't a sequel to Dig, but it's a new turn-based strategy game set in the same IP.

I already considered it. It has no firm release date yet.

I reorganized the OP. Games that got en enhanced version are listed separately, as games there the second entry gets a release soon.