You know what old RTSs are totally awesome? Seven Kingdoms ("Ancient Adversaries" and "II: The Fryhtan Wars").
Years ago, I got a disc with some demos on it, and one of them was for 7KII. That disc influenced a lot of the game purchasing decisions my sister and I made over the following five years (well, all of them, really), and we eventually purchased at least three of the seven games on it. (I can't remember if there were any other games we thought about buying, but the three we got-Septerra Core, Revenant, and Seven Kingdoms II-were all games we both enjoyed and played quite a bit.)
More recently, I was curious about the game, and some careful internet searches later, I discovered that, like a number of low-selling games from the old days have of late, the first Seven Kingdoms (which is often called "Seven Kingdoms: Ancient Adversaries" because it was later packaged with its expansion pack, Ancient Adversaries) has been released under a general public license, and has been updated to run more smoothly on modern operating systems. Which means you can get it for free. (7KII apparently is somehow still providing enough income that Enlight, the company that created the games, is unwilling to GPL it.)
Anyway, if you've ever played an RTS, you know how they work. You look down on the game world, click on units and give them commands, and build units and bases to create and sustain an army with which to overrun your opponents.
Seven Kingdoms was the RTS that dared to be different.
Before games like Warcraft III introduced the idea of heroes who gain massive benefits from experience, Seven Kingdoms gave that feature to every unit (well, except war machines, because they're machines).
But that's a minor aspect of it. Seven Kingdoms (and its successor, Seven Kingdoms II) featured unique systems that forced you to consider how to treat your units, how to expand, and more. Each non-war machine unit other than your king has a statistic called "loyalty," which rises and falls depending on many factors, and enemy units have a statistic called "resistance" which is essentially the opposite of loyalty. It is easier to bring towns under your control with generals (or your king) if the general matches the nationality of that town. (7K:AA messes the math up a bit with its mixed nationality towns, but despite that, it was an interesting feature unique to the first game.) Also, while you could reduce an independent or enemy town's resistance by attacking it, this tends to drive down your "reputation," yet another statistic, which affects both general loyalty and resistance relative to you, and also affects your final score. There are also spies, which work in a way more like real spies than is possible in most games.
While 7K:AA had many features that were removed from 7KII, the things that it had weren't much of a loss (other than water and ships, which I love), because the addition to 7KII was a wonderful one: Fryhtans.
Essentially, Fryhtans are giant, murderous monsters that run around killing everybody and probably eating them. They appeared in the first game as "trolls," essentially annoying enemies with prizes for killing them (another thing featured later in Warcraft III), but in 7KII, you can play as Fryhtans.
For me (and my sister), this honestly makes all the difference: Fryhtans don't have reputation scores, and that means you can be as nasty as you want. In fact, you're encouraged to be as nasty as possible, because Fryhtans have magic that is essentially powered by killing humans. Seriously. (There's also another interesting vibe to Fryhtans, but I like Fryhtans so much that I'm seriously going to do another blog post at some point all about them.)
The second game also fixes a wonky thing I noticed about the first game: AI players in the first will attack independent towns to drive down their resistance, because AI players apparently don't care about their own reputation. (AI Fryhtans, of course, have no compunctions in the second game.) Another nice feature of 7KII is that you can choose to have bigger buildings, although if you're used to playing with the smaller ones, it's disorienting.
Both games also feature a number of other things, like summonable deities and other such stuff, but that's really just icing on the cake.
If it sounds remotely appealing, give that first game a try (you've got nothing to lose, it's free), and if you like that, try the second, too.
From what I've heard, the third Seven Kingdoms, Conquest, was panned by critics; it apparently only carried over some general ideas from the first two, those being the use of "gods/greater beings" and the idea that humanity had huge, terrifying monster enemies (generically renamed demons). It looks like it was very pretty, but that's probably the best thing about it. [/curmudgeon]