@awesomeusername: well that just sucks. I hope the touchscreen stuff in killzone mercenary is optional at least. This stuff is exactly what I was worried when getting a Vita. PSP doesn't have this to deal with!
to make matters worse I just read something about amazing spider man for vita uses dpad and left analog at the same time. game devs are a-holes I tell you what
One thing Killzone makes you do is swipe the touchscreen in random directions when melee killing an enemy. The other thing is with this heat seeking missile killstreak thing. You tap circles on the screen when enemies appear ti send rockets to them. Besides those forced things, Killzones touch features are pretty much optional.
@egg: Story made no sense and was boring, gameplay features like pickpocketing and holding the Vita to a light bulb to reveal secret messages were half assed, multiplayer is complete ass, characters weren't interesting, audio & voice acting were weird/bad now that I think about it, and changing "personas" (outfits) was a boring gameplay mechanic. I'm sure there's more but I don't remember. Top 3 Vita games are Gravity Rush, P4 Golden and Tearaway. Liberation is among the worst.
Obvious choices here is the FFX | X-2 collection. So far I've sunk over 250 hours into both games combined on my Vita, and I only need 4 more trophies to platinum both games (and they're all in Last Mission.... fuck you Last Mission)
Dragon's Crown has an overworld style of adventure game, and you can easily sink tons of hours into it by progressing up the difficulty.
Tearaway is really great, but it's also super short so don't expect it to last you very long.
Ys: Memories of Celceta is supposed to be pretty good too.
FFX is not the "obvious choice". It has randomly triggered encounters which is 1) disruptive to the act of exploration and 2) ruining to the sense of immersion / being there because you are constantly being yanked away. Not to mention 3) in 2014 nobody should buy a game with randomly triggered encounters regardless, and doing so automatically makes you a bad person, and in moral debt equal to whatever the price paid for the game.
The Ys games, the GTA games, Assassins Creed Liberation/Bloodlines, the Midnight Club games, Monster Hunter style games, action RPGs, Gravity Rush, Medal of Honor Heroes or various shooters, and Daxter are all reasonable suggestions.
And you're a bad person for trying to push Ass Creed Liberation onto OP. That game is . I know you said you haven't played it but you're still at fault here. Be gone!