If you ask people what their favorite pre-Disney Star Wars video game is, a lot of people would probably say Knights of the Old Republic or its sequel. Or maybe X-Wing, TIE Fighter, Dark Forces, Force Unleashed, Battlefront, or some of the various other ones. I'm not sure many would even remember Rebellion, which was released in the late 90s only a year or so ahead of The Phantom Menace.
But Rebellion is probably second only to Age of Empires as my favorite strategy game of all time. It is sort of an Age of Empires game, only set in the Star Wars universe.
Like AOE or even Conflict, there's a pretty simple goal: destroy the other side's base and capture its leaders. The Rebellion has to capture the Emperor and Vader and take over the capital world of Coruscant. The Imperials have to capture Mon Mothma and Luke Skywalker and capture the Rebel base, which unlike the Imperials can move around the board.
You get a map of the entire galaxy from the Core worlds of Coruscant to the Mid-Rim, Outer Rim, and Wild Space. Most of the Outer Rim and Wild Space are unexplored, so you can dispatch units to go explore and claim those.
There are resources you need to build ships and troops to conquer planets. So when you take over a planet, you capture any mines it already has and can build more up to however much energy the planet has available.
To build ships you need a Shipyard and to build troops you need a Barracks. The more shipyards and barracks means the faster each unit gets produced. The shipyards and barracks can also be upgraded to "Advanced" ones along the way. But still, to create a Death Star is going to take a while.
One great thing compared to AOE is you can assign your helper droids (C3PO for the Rebels and some evil droid for the Imperials) to manage your resources for you so you don't have to supervise building mines and dumb shit like that while you're trying to win a war.
There are a few different ways to take over a planet. The most direct is to launch a planetary assault. Typically you want to destroy ground forces from orbit with your starships and then land your troops. Once you do, you'll need to leave a garrison so there's not an uprising to tie up your resources or even to overthrow your units to make the planet neutral or go to the other side. Another way is to dispatch a diplomat (like Princess Leia for the Rebellion) to cajole the planet to join your side. That only works with neutral planets, not ones siding with the other side, though you can maybe eventually convince them to be more sympathetic to your cause. For unclaimed planets, you just land troops and leave a garrison.
Making it more difficult, is that each planet can have defenses: shields, ion cannons, or laser cannons. You can't bombard a planet from orbit if the planet has a shield. Or if it only has a weak shield you need a ton of firepower to overwhelm it. Bombarding a planet with an ion cannon could disable one of your ships and bombarding a planet with a laser cannon can destroy one of your ships. For that reason you usually want to try taking those planets by other means. You can use commando units or certain characters to sabotage the defenses so you can then swoop in and take the place over.
Besides the characters I've mentioned, you get all the main characters from the original 3 movies and a lot from the "Expanded Universe" at the time. You start out with a few characters but then you have to "recruit" more using some of your characters--Mon Mothma/Luke/Leia/Han for the Rebels and the Emperor/Vader for the Emperor probably have the best chances to recruit someone. Characters have different abilities and uses. Some like Leia are diplomats. Some like Lando or Thrawn are useful to research new weapons. Some like bounty hunters and special forces types are more useful at sabotaging defenses or capturing other characters. And some like Ackbar or Piett are more useful for commanding your fleets. Force users like Luke can train to increase their skills. At the start of the game, Luke is like at the start of Empire, but at some point he'll run off to train and come back as the Return of the Jedi version.
One funny little thing is you can send the Emperor on missions. If he succeeds in his mission he'll of course take all the credit. If he fails he'll say, "You did not adequately prepare me for this mission. And it has failed." Sounds like pretty much every boss I've ever had.
Like AOE or Conflict, you start off with only limited weapons you can build. Stuff like basic troops, X-Wings, TIE Fighters, corvettes, or light cruisers. As you research, you get newer and better stuff like A-Wings, B-Wings, TIE Defenders, Mon Calamari Cruisers, and Super Star Destroyers. The Imperials get the Death Star while the Rebellion really has no equivalent. What sucks with the Death Star is if you actually blow up a planet, basically the whole galaxy will start turning on you. What's the point of having it then?
If you choose, you can control the battle between forces. I always found that too slow and clumsy. So I would always choose to simulate the battles. But you have to make sure you have enough firepower to do the job then because otherwise you'll probably lose and your units will be destroyed or damaged and have to retreat to the nearest planet you own.
Given the size of the galaxy, a campaign can take a long time. You can do a shorter game where you only have to take a base, but the longer game is more fun.
If you're the Rebellion, you start off mostly in the Outer Rim with your base on Yavin, though you might have a couple of Core or Mid-Rim worlds like Mon Calamari. What you want to do is explore the Outer Rim to build up resources and try to convince some neutral planets to your side. Only then can you try to defeat the Empire's Core worlds. And you'll want to move your base around a couple of times to make sure it's not too easy for the Empire to find.
As the Empire, you get a lot of Core worlds, so you have better resources than the Rebellion. Still, you need to shore up the Core and start taking planets in the Outer Rim to acquire more resources. You can send units to Yavin, but it's likely the enemy will be gone long before you get there.
Traveling around the galaxy can take a while, especially from one side of the Rim to the other. Going from Yavin to Hoth for instance would basically take a fleet months. For that reason, you need to have shipyards in multiple areas so you have forces able to easily reach almost anywhere. Think of it like how the US has a Pacific Fleet and Atlantic Fleet so they aren't always having to send ships from one ocean to another.
Playing the game a couple of years ago on Steam it is a little weird in that you don't have the planets and characters from the prequels or any of the TV shows like The Clone Wars or Rebels. So if you play it now, you might wonder, where's Naboo? Or Geonosis? But they didn't exist yet since the game came out just before The Phantom Menace.
As much as I would have liked it, I don't think they ever made an expansion or sequel. It's too bad, because it is a really fun game if you like strategy games.