I like this twist.
PS2:
Shin Megami Tensei III: Nocturne/Lucifer's Call:
Best turn-based combat system in a game, ever. It's fast faced and challenging with a whole bunch of tactical depth. The demon negotiation, fusion and collection is incredibly addictive; I've put more hours into this than Pokemon, at least! The story isn't the very best in a game, but that doesn't mean it isn't damned good. With 6 different routes relating to four factions, there's a ton of replay value. The game doesn't have a ton of character focus, as you spend much of it alone. It poses a lot of philosophical questions and your behaviour and choices throughout will determine which of the 6 paths you will take. One of the most interesting features of the plot is that the goal isn't to defeat the main "villains", but to decide which, if any, you agree with the most.
In short, it's an incredibly fun, open-ended, monster-catching dungeon crawler. The best JRPG ever made.
PC:
Planescape: Torment:
I've always been a little torn on this one because the combat is so bad. Unlike many other RPGs, it can almost all be avoided but, in dungeons, that's really hard. The actual mechanics aren't too bad; it's pretty much the same as Icewind Dale (which I love) but the encounters are just so poorly put together. The Curst Prison, for instance, just throws hundreds of high-level guards at you and it just isn't fun. The thing that makes it worth it, is a combination of the rest of the gameplay and the narrative. It has both some of the best writing and the best over-arching story of any game I've played and just exploring the world, engaging in debates (a viable way of defeating bosses) and solving puzzles is ver fun on its own. The game would have been much better if it were a point 'n' click adventure, but I love it all the same.
PSP
Final Fantasy Tactics
Second only to SMTIII in terms of brilliant turn-based combat, with a fantastic political story (that sadly goes mental about 2/3 of the way in, as FF plots are wont to do) that explores heavy themes such as classism. It's really quite odd for a Final Fantasy, with most of its lore sounding like something out of a history book. It's largely quite morally grey and a lot of it seems to be quite heavily inspired by the Thirty Years and English Civil wars. The game has a great story, with great grid-based combat that even includes a cool monster-catching mechanic. Troops can die permanently in battle and you can hire more from the Warrior's Guild to bolster your ranks.
It's extremely fun to play, with an engrossing story. It's just a shame that neither translation is especially great. The PSP one disappointed me because it was the same team behind the Vagrant Story translation, which I maintain is the best Japanese to English translation ever, in any medium.
I chose the PSP version because it was the only one released in Europe. I have played the PS1 version, though. Also, this may be replaced by Tactics Ogre which I am absolutely loving.
PS1:
Vagrant Story
A fantastic translation of a great script that tells one of the best stories in an RPG surrounds an incredibly difficult, but oh-so very satisfying solo dungeon crawl. The combat is kind of real-time, but you pause the game to take actions. A large sphere surrounds you and you can choose to attack any body part within range. If you have good timing, you can then chain combos together creating various effects, ranging from dealing more damage to healing you, to inflicting status ailments. The game has a ridiculously in depth weapon crafting system that you WILL learn if you don't want to die. It isn't about picking the strongest tool, but the right one for the job. The only problem with the game is how little it explains its less intuitive systems. But if you want a dark and extremely difficult solo-character RPG with a great story that ranges from political intrigue to horror without losing focus. Buy it.
Megadrive:
Rocket Knight Adventures:
Shock! Horror! Something that isn't an RPG! I wanted to pick Phantasy Star IV, but my heart belongs to this.
This is the best side-scroller ever made. Great visuals, great music, tight controls, varied and interesting levels with a challenging, but fair difficulty curve. Plus, you play as a possum with a rocket pack and sword that shoots FIRE. It has scrolling shmup sections and a giant mech battle to break up the platforming and not once does the quality falter. I just wish it were longer.