Especially the first one, that was last generations 'wow' moment for me.
However, if you like action games (and your purchase of the God of War games tells me you do) you should pick up Bayonetta. It was made by Hideki Kimiya, the same man who created the Devil May Cry series, and it works as an evolution of that. If you can handle some bizarre/goofy story and characters, you'll be rewarded with some of the fastest, most in-depth fighting in an action game and tons of imaginatively-designed creatures and boss battles. One VERY IMPORTANT caveat: if you do get this game for the PS3, make sure you download the patches for it. Otherwise, you will deal with tons of load times (even menus have load times) and slow-down.
Got the Bioshock trilogy on Steam for 15$. Usually that's the best deal for things now. Some of the stuff, e.g. Blood Dragon, require you to download a bunch of DRM nonsense though.
BTW, I was playing the 3D Bionic COmmando on Steam, and it's awesome. The whole point is that you have to use the arm for most of the fighting, so of course the weapons kind of are a little unsatisfying. I would say it's the best "flinging stuff at enemies, including other enemies, to defeat your enemies" game since Super Mario Bros 2. The arm is better than HL2's gravity gun.
It seems to respect the source material as far as I can tell. Some of the ads for Pepsi and such have been patched out. It seems to work well enough with a keyboard and mouse.
Of course, the 2D remake is great (BC Rearmed). If you get both on Steam, then you can play as the old school Spencer in the 3D game.
The only beef I have with these BC games is the art style is too Western; the original was distinctly Japanese.
Some more titles I forgot to mention:
Deadly Premonition: Director's Cut
Driver: San Francisco
Watch Dogs(there's four missions exclusive to the Sony versions of the game)
GTA IV and Episodes From Libert City
Dead Island series
Deux Ex: Human Revolution
Dead Rising 2: Off The Record
DMC : Devil May Cry
Killer Is Dead
Max Payne 3
Shadows Of The Damned
Whether or not FF13 is worth your time depends on what kinds of games you like best. If you prefer, say, Call of Duty to Skyrim, and generally choose JRPGs over WRPGs, love tight, strategic combat systems, and are very, very patient--you might like FF13. Otherwise, you might find that it's extremely boring and seeks to stifle your creativity and sense of free choice at every turn. FF13-2 I wasn't able to finish because the event scripting was so bad and because the only character I really liked from 13 (Lightning) was AWOL. I don't think I'll play 13-3.
FF10 HD is great. A true classic worthy of your time. Definitely buy it. I'm already replaying it (on Vita).
Demon's Souls is my favorite game of all time (this seems to be true of many other ps3 owners I've met as well).
I don't know what you should buy. I only know you need PS+ and the choice is made for you. I mean, they give you a trillion games.
I also don't think you're a generation behind. There are about 3 years left before most games can be "current gen" exclusives. At least. With development costs being what they are, competition being what it is, and the install base on the 360 and PS3 being as large as it is, things are going to go long yet. Also, some of the biggest online games, likely to be supported for years, are on "last generation." Titanfall is there, and I predict the next one will be too. I believe Destiny is there when it comes out. And the PS3 and 360 still have titles announced for 2015 already. It's pre-E3 2014, and the PS3 and 360 already have lineups announced for next year. You'll be set for a few years before you're actually a generation behind.
Is it worth playing into the first Killzone much? It's about as bland as the reviews said it was, judging from the first two hours or so. Just wondering if it picks up later on.
I remember loving Killzone Liberation, the third person shooter that kinda was modeled after the overhead stages in Contra (only using a 2006-era fps engine and some fps concept), and thinking it was excellent, and maybe the reviewers of KZ1 were jaded professional video game players. But KZ1 does seem pretty damn bland.
I'll just find a way to replay Liberation, and call it a day if so. I'm playing the fun Halo rip-off of KZ Liberation on my phone, and am reminded how excellent that game was.
KZ2 is great, a lot of fun. This series is interesting not because it has original ideas, but because it takes the two most common concepts in FPS's--space marines and Nazis--and combines them into good space marines fighting Nazi space marines.
The first Killzone was hyped up big time as a "Halo-killer", and it didn't exactly live up to that name, still you might want to play it if only for the sake of better understanding the story in the sequels.
Good Space Marines with American accents fight Nazi Space Marines with non-American accents.