Oh, nice thread and lists (and that one from OP too!)
It's always hard to choose. I tried recently, though.
Of course it will be changed in the future, because i have pretty big backlog...and i'm not including stgs here.
PC
Anachronox - space odyssey rpg/adventure, full of funny jokes, curious characters and different worlds to explore. Has it's flaws and kinda unfinished but still felt in love with it.
Binary Domain - tps from Team Yakuza, and so what? Well, it's awesome - in game process, in overall presentation, in storytelling with social background. Though, starts a bit slow and "generic", but gets better quickly.
Clive Barker's Jericho - sure, you can't jump here. Sure, sniper girl is overpowered. Sure, it's cheesy. But, whatever. I like it. Gorgeous enemy design and overal gore aesthetics (sure..), some interesting places and pretty ok gimmick with "play as team of differently specialised units".
And yes, i played Undying too and it's gorgeous, but that's another story.
Cryostasis: the Sleep of Reason - interesting first person shooter/survival from ukrainian developer Action Forms. Besides some silent hill'alike monsters, time travelling thing (a bit similar to Ghost Trick in it's idea) and cold as hell atmosphere, it has really soulful plot about how one people's ambitions and cowardness costs others their lifes.
Daikatana - yes i said it. Dai-ka-ta-na. I'm still "wtf?!" that people continue to spread lies about how it's "worst game in the world" or smth (unless they mean stupid N64 release based on beta). In reality, it's very decent fps that was trying to do different things too early and for some reasons it's also was late. The only real problems DK have is several bugs and stupid AI of "companions", which in addition to ULTRAHYPE it had before release made people really HATE it. Well, maybe because i played it for the first time only ~7 years after release, i liked it. It has good level design and by that i mean structure of levels, not decorations. It has awesome weapons, different for each of 4 episodes. It has oustanding soundtrack, dammit. Some nice challenge, though some areas could be too generous for medkits. And it's multiplayer is damn fun (mostly because of mumbo jumbo with weapons). Atm, there is fan-made patch that fixes most frustration moments (though there 've always been a fix for stupid partners - play it in co-op, lan/web. Or even solo, you loose cutscenes but get rid of companions). Also, some multiplayer servers supported by little community of fans.
Dark Souls - love it for fencing. Also, gorgeous level design (overall): i mean, all those interconnections and "hey, i've seen that chapel from streets below and now i'm here". And, of course, feelings which you get after successfully defeating someone.
Deadly Premonition - "Twin Peaks: The Game", some could say. For me, it was more about ridiculous characters =)
Half-Life: Opposing Force - imho, most atmospheric of series. Also love that Race X and crazy weapons.
KISS: Psycho Circus - Nightmare Child - i'm not a fan of that band, but liked game pretty much. Monsters, levels, weapons, everything is cool.
The Last Express - oh, wait, point & click adventure! But story is pretty good and it really captured a feel of train voyage.
Pac-Man Championship Edition DX Plus - who needs medicaments anymore?
Pathologic - crossgenre survival game from russian studio Ice-Pick Lodge. Very unique thing, you can read about it at hg101 or rps to get some picture.
Populous: the Beginning - very fun god sim/RTS. Landscape terramorphing, tornados and volcanos and everything else.
Quake - still love it's pacing and art direction.
Vampire: the Masquerade - Bloodlines - for me, it's the only true inheritor of Deus Ex 1.
Zeno Clash 1/2 - first person brawler/shooter from chilean developers. Interesting artstyle and world.
Genesis (+CD)
Tiny Toon Adventures: Buster's Hidden Treasure - my fav platformer. Has nice variety of levels/zones.
Vay - nice jRPG with humour and, wow, fixed inn prices. Ha.
SNES:
Chrono Trigger - one of first games that managed to make me play it through the whole night.
Demon's Crest - was totally impressed even though played it for the first time only in 2012 or smth.
PS1:
Baroque - harsh dungeon crawler (+roguelike elements) with surreal monsters and creepy atmosphere.
GeGeGe no Kitarou (2003) - pretty cool Ghouls'n'Goblins-style sidescroller based on classic manga.
Parasite Eve 1 - horror-jRPG with epic sense of total apocalypse and wonderful soundtrack.
Persona 2 Innocent Sin - oh, in old times Persona series wasn't about waifus..it combined references to occultism, psychology, japanese social traditions and many other things. Though, those random encounters are really exhausting.
Final Fantasy Tactics - loved it for gameplay, but didn't expect nice plot as an addition.
Rising Zan: the Samurai Gunman - wow, wow, wow, what a game! pre-DMC slash action with God Hand's jokes and atmosphere. Camera is uncomfortable, but overall it's nice pack of fun.
Armored Core & Armored Core: Master of Arena - rapidly controlled mechas X trippy electronica ost = win. Gonna prepare for pain in ps2's Last Raven.
Dreamcast:
D2 - bizzarre horror action-adventure from Kenji Eno, with cheesy scenes and absolutely beautiful music.
Maken X - my fav game from Megaten-related subfamily. Has arcadey gameplay and cool designs from Kaneko. PS2 port has some cool bonuses but i woudn't recommend that one.
PS2:
Bully - why not) It's hilarious
Devil May Cry 3 - only played it this winter, dunno why i didn't do that earlier. Marvelous!
Shadow of Memories - heartwarming adventure game with some cool twists and time travel.
Killer 7 - oh, man. It's like Guy Ritchie's "Revolver" movie. Mind = blown
Shadow Tower Abyss - maybe, most interesting game from From Software (you could remember them for King's Field, Armored Core, Echo Night, Demon's Souls, Otogi etc.). It's dungeon crawler that could be viewed as step between KF and Souls series. Love it for atmosphere, strange mix of themes (aliens, mutants, wizards etc.) And you can cut limbs of enemies so they change their moveset. Also, had guns before Bloodborne! A bit too easy, though (unlike ps1's Shadow Tower).
Shinobi - i know many people hated it, but whatever. I love it's temp. This game got the rhythm.
Silent Hill series - LOVE THEM. I think i gonna like Forbidden Siren (especially 2nd one) too.
Virtua Fighter 4 Evolution - i just like it, maybe i'll afford Naomi version supergun one day, who knows.
Nintendo DS:
Flower, Sun and Rain - surreal adventure, port from PS2 (that version has better gfx/audio but japanese-only). For me, it has one of the best plot/characters in games ever, but it's pain to play and you need to know what happened in it's prequel to get the whole picture (The Silver Case on PS1).
Shantae Risky's Revenge - cool and colourgul platformers with multiplanes gimmick. Nyah!
The World Ends With You - i think it captured concept of loneliness in socium w/people interactions better than recent Persona games.
PSP:
Hammerin' Hero - lovely sidescroller from Irem. You're a man with a hammer (...or something else. A big tasty fish, for example), who helps citizens against evil corporation.
Lumines - it's especially good at 4 a.m.
Outrun 2006: Coast 2 Coast - one of racing arcades where i do feel the speed. Awesome vgm, too.
Pix'n Love Rush (Minis) - love this retro-inspired platformer from french devs. Pretty high replaybility for me.
Prinny: Can I Really Be a Hero? - "Dark Souls of PSP"
iOS
Rimelands: Hammer of Thor - basic, but charming turned-based rpg
Chaos Rings series - jRPG from Media.Vision. Loved them, but 'm angry at coming CR3 which looks BAD.
Groove Coaster Zero - rhythm game from Taito. Awe-so-me music (imho), Rez-style visuals.
Nihilumbra - platfotmer where different colour paint gives different properties.
Swordigo - looks like some shareware from 2000s but plays well.
1-bit Ninja - for me it's best "Mario clone" ever. Too bad it's not ported anywhere else.
Ok, that's all for this time, hope i'll come back in the future with post about arcade titles one day (ports, MAME or even find a cab in my city, haha)
