Another oldie (which is seeing new life through both Steam release and release for iPad and Droid), Knights of the Old Republic is an early Bioware creation and perhaps one of the first role-playing video games set in the Star Wars universe. Rather famously, this is also a leverage of Bioware's existing "port" of paper-and-pencil Dungeons & Dragons mechanics into a video game. Lurking under all the weapon stats and Force skills is a "D20" system; critical actions are determined by rolling a 20-sided dice against a calculated value.
In D20 fashion, you have character classes (which control your starting points, which skills you are allowed to take, etc.), you have characteristics (the old Strength, Dexterity, Wisdom, Charisma etc.), you have skills (which unlock certain options and add bonuses to various rolls), and feats (which do the same, only generally more globally; a feat might give bonuses to a half-dozen different skill rolls).
Oh, and of course you have magic...err, Force powers.
It is role-playing, with early iterations of what would evolve to become the (in)famous Bioware Dialogue Wheel, and the superimposition of a sliding scale of morality (Light side versus Dark side, naturally). A great many of the critical decisions in the game are made via dialogue choices, and these will truly shape the game -- and in more than determining whether you stay Jedi or turn Sith.
An interesting aspect to the dialogue choices is that you generally have equally "light" and "dark" choices available. Which gives you more options in each encounter, and gives you more of a feeling of freedom, but I think this mechanic gives you something else as well (perhaps unintentionally); even when you are playing at the lightest of the light, trying to be the kindest most helpful boy scout of a Jedi possible, there is always this temptation to just tell the squabbling couple to shoot themselves and save you the trouble of dealing with them anymore.
And I'm not giving away any spoilers (probably) to comment how appropriate this lurking temptation is for the character you will be playing!
The dialogue is generally strong; but above even the voice acting, there was someone on the development team who could really, really write dialog. I am humbled. I could not write some of that dialogue. And I'm talking not about the necessarily formulaic set-pieces of the grand plot, I'm speaking of the banter that occurs with several of the stand-out characters.
Jolee Bindo: imagine Morgan Freeman doing a True Neutral version of Ben Kenobi. A master of snark, a true guide, and refuses to admit he is teaching you or get into any of that mentor foolishness. Exasperating and warm all at the same time.
Canderous Odo: taking the Extended Universes' fondness for the Mandalorian to the ultimate extreme, he is a Manly Man doing Manly things. It is the voice acting that sells this one; he is so over the top (yet so utterly committed and serious) it is totally worth spending the time to talk to him. Frequently.
HK-47: A droid with an attitude that has to be heard to be believed. Where Jolee is an artist of the snarky retort, HK-47 employs them like a stiletto.
Carth Onasi: every conversation with him goes haywire, until he is left practically unable to form words. Someone studied at the feet of the great playwrights here, because the dialog scenes with him have that avalanche in motion effect of an argument in a Neil Simon -- everything each of you says ends up coming out wrong, he takes offense, tries to apologize for taking offense and only digs himself in deeper...well, I just can't describe it. Like I said; this is the sort of thing I wish I could write (and can't.)
And, yeah, I turned to Mission Vao a lot of the time, as her Rogue skills were essential in cracking computers and disarming mines. She was the first in my party with good sneak stats, too, so I more than once sent her out alone. And since I hated to break up the pair, Chew.., err, Zaalbar usually went with her. Although the wookie was practically useless in combat until I figured out I actually had to equip him with a decent sword before he'd stop trying to pound everything with his furry fists. Why he never uses the bowcaster he's dragging around, I don't know. It's probably somewhere down in some nested menu.
Although you are eventually traveling with up to nine (depending on choices you made, such as whether you both spare Juhani and turn her from the Dark Side), you can only take two at a time. And it is often worth taking specific ones (like bringing Zaalbar to Kashyyyk), even when the game doesn't explicitly require you to.
One major change from, say, Mass Effect is that your own dialog isn't voiced. This made for me a small emotional disconnect. I didn't always feel as if I was part of the conversation. Over half the dialog is in various alien tongues (subtitled) which is very cool and adds to the feeling of the Star Wars universe -- but the aliens also always speak long. It takes Zaalbar longer to say "no" than it apocryphally does for Wotan to sing it (Wagnerian opera joke there). And if you page through, you risk hitting the key just as the dialog ended and accidentally selecting a response on the next screen.
Related to this is, once again, major fights and, worse, mini-games that are placed directly behind an un-skippable cut-scene. Worst is one where you take off in the Ebon Hawk (really?) and there's a long scene on Darth Malak's flagship...and then a scene on your ship...then you are trying to win a frustrating and quirky turret mini-game. Which means if you miss, it's back to fifteen minutes of cut scenes for you before you can try again.
I started my game as a Scout with no intentions of being dragged into the whole Jedi thing. I specialized in blaster combat, meaning to keep my enemies at a distance. Well, you get that lightsaber whether you want it or not. And it did so much more damage than anything else I had, I quickly found the best combat option was to place myself in front, soaking up enemy fire, while my buddies Canderous and HK-47 poured down blaster fire from a safer distance. Making lots of gleeful comments all the way -- the fun with these characters, really, with all your potential party members -- is not just in your interactions with them, but the way they comment, butt in, and otherwise act out in public.
And, yeah...with Blaster Deflection droids and mercenaries and the like are a little less of a drain on your health packs. And Blade Throw is even better than grenades for doing area damage; an incredible leveler for when you have close-packed enemies. But for all of that, it is a bit annoying to be forced into lightsaber for everything. Thing is; over half the baddies are animals or Sith or otherwise things that close to melee range. Sniping at them from a safe distance only really works when the path-finding AI can't figure out how to get to you (I had Mission shooting a Rancor in the ankle for about ten minutes once until I finally figured out how to take it down.)
So embrace the lightsaber. The Force? Not so much. Force Whirlwind and Force Push are a lot of fun -- the latter was exceptionally useful for getting distance to use a lightsaber throw -- but pretty soon everyone you meet is Force resistant. For that reason, Force Persuade is totally useless (plus always seemed to me a pretty horrible thing to be doing to people). Sink your points in Charisma et al instead.
Oh, yeah. And using the Force to heal. This is very much video game in that who wins a nearly-equal battle basically hinges on who has the most health packs available. Although you can cheat a little in this game; you can instantly zap back to "camp" (aka the Green Pigeon) and have health fully restored, then zap back to wherever you were. And if you want to really abuse the camp mechanic, go around the Canary Canary and sponge extra grenades et al off your crew. Zaalbar will groan and roar for five minutes but at the end of it will have created a brand-new grenade out of spare parts. And you can keep going back until he gets tired of it.
The sound design is excellent. On the few minuses, background sounds sometimes come close to covering up dialogue. Tweaking the sliders didn't seem to help. On the plus side of the ledger, the music is excellent orchestral simulation with a very strong John Williams flavor (including direct quotes, which fortunately are not abused). It is subtle as well as martial; there's an great little bit that plays sometimes when you are heading to a new world that combines something very much like the famous opener in the skies over Tatooine with a subtle shimmer of glockenspiel that evokes the "here we are at a new planet" opener in original series Star Trek.
Graphics are decent for when they were. Kudos for bringing so many of the creatures from Star Wars across, although I did tire eventually of seeing Twilek everywhere. Limitations of the number of character models did lead to some odd moments of the "Wasn't I just talking to you on Dantooine?" moments and sometimes the face really didn't match the voice actor. One oddity that may be a artifact of the number of models and the color space or may actually be a refreshing choice is that unlike Billy Dee William's practically solo performance, a seeming majority of the human characters are dark-skinned. Perhaps one of the developers had been reading Ursula K LeGuin's essays?
Another graphical amusement was a bar scene where I presume they either couldn't spare the polygons for drinks or even chairs, or hadn't written an animation for drinking, because all the patrons could do is bob up and down "drinking bird" style -- so much so the first one I saw I thought was trying to throw up.
The planets were generally excellent -- the forest floor of Kashyyyk being the major disappointment (but how could any game match up with the lush complexity of the Star Wars Comic Book?) There is also in the Steam version of the Mac port way too much bloom being used to demonstrate the hot deserts of Tatooine...quite enough bloom to hide any number of Tusken Raiders, whether or not they chose to ride in single file.
But otherwise the settings were distinctive, and I welcomed each new world and the chance to immerse in the deep, surprisingly subtle stories (the wookies, in a clear echo of the Ivory Coast, are selling their own people into slavery in trade for weapons to use in local conflicts), and all the little stories and problems you will find yourself involved in (basic RPG tip; don't turn down any side quest. It might just get you a couple credits, but it also might be the only way to get the key you need to complete the mission).