Minus Republic Heroes (which I've not actually played), the entire collection is actually pretty damn solid.
Dark Forces uses DOSBox, as it's a fairly ancient game at this point, but I believe I read somewhere that the Steam version of the game has been updated to use a modern control scheme (the original release was long before WASD and mouse-look were standard for FPS games) which means it should be fairly easy to pick up and play without too much messing around. It's old-school, but still holds up pretty darn well.
Dark Forces II - Jedi Knight might be a little more tricky. I don't know how much the Steam version of the game has been updated, but in a general sense Dark Forces II is a pain in the ass to get running on modern PCs, and ATI graphics cards using Catalyst drivers more recent than 13.1 or the 13.2 Beta 7 (which are dreadfully old) crash the game if you try playing with 3D Acceleration (and without it, it looks... old). Dark Forces II takes the Dark Forces formula and then switches things up by giving you a lightsaber and Force powers a few levels into the game, and implements something of a morality system by which you can kill innocents to build toward the Dark Side if you want, and there are separate powers each for the Dark and Light Sides of the Force. Also, the game actually has two different endings depending on which side you end up being.
Personally, I wouldn't recommend the expansion Mysteries of the Sith, but that's mostly because it has the same engine troubles as Dark Forces II and looks even worse using software rendering.
Jedi Knight II is a bit more modern. It still uses old-school shield-and-health system by which you need to find health stations and bacta tanks to regenerate your health (or use the Force once you can), still gives you guns and a lightsaber, etc. etc., but adds in multiple stances for the lightsaber combat which have different attacks, and different strengths and weaknesses.
And then Jedi Academy is the last title in the Dark Forces series, though it focuses on a different main character (which you can choose yourself from a moderate character customization screen) and has a much greater focus on the lightsaber combat than any of the preceding titles, even going so far as to eventually allow you to either dual-wield lightsabers or use a double-bladed one (I believe the campaign lets you do that; It's been a while).
Then there's Battlefront II, which is absolutely fantastic and a bit hard to explain. It's a... grand warfare game, I suppose. The actual battles take place on rather large maps, and can include either being on foot as a foot-soldier or speeding across the grounds, through air, or through space in vehicles. It works on a class system for the units, and you're basically playing a third- or first-person shooter version of an actual Risk battle, whereby each side of the conflict has a certain amount of reinforcements and you're trying to deplete the opponent's before your own are gone. Maybe somebody else can describe it better, but it's pretty damn good.
Knights of the Old Republic and Knights of the Old Republic II are, of course, D&D-inspired RPGs made by Bioware and Obsidian respectively set long before the timeframe of the films. They are extremely solid titles, especially if you like old CRPG combat, but a word of warning that they may not be the most stable on your system. Particularly KotOR II, which was notoriously released in an unfinished state, literally. Speaking of which, if you do pick it up, do check out the Sith Lords Restored Content Mod for KotOR II, as it's a pretty big mod which aims to reintroduce all of the things that had to be cut from the game because Lucasarts told Obsidian to suck it up and release the game sooner.
Republic Commando is a tactical first-person shooter. While it's not the most complicated or difficult one around, it's damn competent at what it does and really makes you feel like you're in command of a squad of elite soldiers. It does have a few issues with modern systems, such as having Bump Mapping turned on in the options crashing the game when you try to start up a new game or needing to be tweaked to support widescreen resolutions and having dismal mouse acceleration in the menus (thankfully mostly absent from the actual game), but that's mostly stuff you can easily tweak by checking out its PCGamingWiki [http://pcgamingwiki.com/wiki/Star_Wars:_Republic_Commando] page. (I would recommend checking out the PCGamingWiki pages for most of the other games if you have issues, too, as it happens.)
And I've not actually played Starfighter or Empire at War, but I'm led to believe they're a pretty decent flight sim and pretty damn good RTS respectively.
Then we come to The Force Unleashed, which is... basically the black horse of the collection. Personally, I don't think the games are that bad, but they've got a lot of problems. The combat is the high point, thankfully, but it doesn't really open up early enough in the game and can become fairly repetitive, fairly quickly. Which wouldn't be too much of an issue if the level designs weren't incredibly odd and visually non-distinct; Seriously, The Force Unleashed is one of the only games I've played in the last few years where I actually got turned around and ended up lost, and it's not really that complicated in the first place. But the biggest problem, with both games, is probably the length. The Force Unleashed is already an incredibly short game (roughly six hours or so for most people on a single play-through), but The Force Unleashed II somehow manages to be even shorter. And honestly, the story is pretty forgettable. Aside from being the same fare stuff like Dark Forces II already tread over a decade earlier, it's just not very well written or handled, and mostly serves to drag down the otherwise pretty solid gameplay. Also, the UI is pretty bad. As in, "How the hell do I open my upgrades menu, WHY AREN'T YOU TELLING ME THIS, GAME!?!?!?" bad.
And I haven't played Republic Heroes, but it's gotten overwhelmingly negative response from pretty much everyone, so I don't feel that I really need to.
