For old school RTS, Total Annihilation or if you fancy something a bit different then The Settlers II (Pioneers of Pagonia is a more modern remake). I grew tired of RTS and moved on to turn-based but Stellaris is one that recently drew me back in.
For tactics I'd say Advanced Wars, Fire Emblem and Disgagea are decent shouts. Into The Breach is probably my favourite indie of the genre, a lot of strategy packed into a small game.
If you like turn-based then Civ has always been top of my list.
It's not real time but Civilization is a must for any strategy fan. I personally recommend getting V and all its expansions, it's peak for me still. Some like VI but I could never get into it.
Even as a Protoss main, Wings of Liberty (the free Terran campaign in SC2) is by far the best in the game. I've replayed it at least once a year since it first released. Mass marine/marauder/medic backed by tanks is so much fun to play with.
If you want to try an RTS that does something different, check out Against the Storm. It's an RTS, but there isn't an "enemy" so to speak. Instead, you are 'fighting' against the environment, trying to solve your economic and social problems before you are overwhelmed by external factors imposed by the level you are building on.
The game continues to evolve as your understanding of its various systems grows.
I'm getting into the Dominions series, recently picked up Dominions 6. You take control of a faction and try to spread your pretender gods influence enough to ascend to be the one true god. Combat is auto resolved but you can watch the combats and the mechanics are very detailed. I made a god that was a sentient glyph that bestowed fire resistance and flaming weapons on my faction of desert dwelling spider riders. Another time I was a sentient fountain of blood with innate abilities to raise an army of mindless skeletons so I could stack troops in masse.
Its a little clunky in the interface but once I learned what did what it because very engrossing
I can't get over the UI, in sure it's good like with Dwarf Fortress, but I would ask how long it took you to feel like you had a bearing on what was going on/fun?
Oh not as long as original Dwarf Fortress, that's for sure!
I had a friend who has some experience explain how to navigate the interface, and generally what each resource does, and after an hour or two of fussing about I got used to it. Some times I will misclick, because right click is sometimes "go back" and sometimes "show more detail" but aside from that its easy enough.
The core mechanics are very easy. Conquer provinces to increase your domain, build stacks of units to fight battle and test different strategies for what works against what.
The Homeworld series is great with fantastic campaigns (minus Homeworld 3 I've heard, not even played that).
I'll also throw in a classic Imperium Galactica 2 because I still think for a 90s 4X RTS it has so many elements that I've just not seen replicated since. Though usually short and quick, it has fully simulated and controllable space and ground battles; espionage; diplomacy; you assign your unlocked tech to hard points on your ships... It's Stellaris but better in most ways, imo.
Yeah, I recently replayed homeworld 1 and 2 and they hold up well. Still haven't played Deserts of Kharak but that looks good too. I've not played 3 either but unfortunately I've heard it's not great.
I mean, obviously play the Red Alert games too. But Generals: Zero Hour was BIG fun in the day. A bit hard to get it to play nice with modern computers, but it was recently added to Steam so its at least legally acquirable again.
Age of Empires 2, obviously. Still the GOAT of Age. Its latest released still gets updates, which is great.
IDK about it being a "must play," but I actually quite enjoyed the strategic/tactical RPG Tuned Hearts, for the Japanese PC98 series of home computers. Im not much of a fan of turn based games in general, but something about Tuned Hearts kept me playing. IDK if it was the battle art or the hilarious enemy characters, but either way I enjoyed my time with the game.
The PSP had Joan De'Arc, which I think is based on an anime, but I could be wrong. It plays similar to Final Fantasy Tactics or Fire Emblem, I think. Not a bad little game.
For 4X, I like playing Stellaris. Granted, every time I play my saves get massively bloated and end game lag is unbearable sometimes due to fleet sizes, and the developers update the game so often that either my save breaks or the systems are vastly different from whenever I played last, but aside from that the game is a lot of fun. If a real time 4X strategy space civilization game sounds interesting to you, I'd give it a shot. Otherwise for turn-based, Galactic Civilizations III from Stardock was my go-to.
One game that we always play at LANs is Spellforce III . It's got a great old school RTS vibe while throwing some new stuff in the mix and there's a free version of the multiplayer which gives it a really low barrier of entry.
I haven't seen Halo Wars mentioned yet so I'll nominate those games. Both 1 and 2 are insanely fun and they control surprisingly well on Xbox if you dont have access to a PC. I've put a couple hundred hours into both games on both Xbox and PC, but I do prefer M&KB controls even if it works very well with a controller.
Cutscenes are fucking awesome in both games as well!
Another game I'd like to bring up is Stellaris. If you're a sci-fi fan and like 4X strategy games then I can't recommend this game enough. I've put 630 hours into the game since I got it back in 2019, being able to role play a custom or sci-fi inspired empire is great. If the amount of DLC puts you off, then look up cream.api. Getting them for "free" is easy.
I'm presently replaying Command & Conquer Red Alert 3 and love it. The cast for the FMVs is all-star, the game itself is a super refined version of Red Alert 2 (itself an all-time classic) and the story has no bearing on the rest of the series so it can be played in isolation with no advance knowledge of C&C
Some of the campaign missions are really good with a nice variety too. I've been re-playing some on the hardest difficulty and it's a real time hog but good fun to spend 2 hours on a mission!
Medieval 2 Total War. It's the best Total War game and one of the oldest. It has a basic campaign map where you create and manage armies which you then use to go into a real time battle with thousands of units. There is nothing as satisfying as routing the enemy with a massive cavalry charge into the rear when they're in hand to hand infantry combat.
While it might not fit the vibe (and you might already know it), I feel like Songs of Conquest needs to be mentioned, being a Heroes spinoff. It's an interesting twist on the formula, with lovely graphics, some things streamlined and some interesting new mechanics (like the essences for spellcasting).
While it's not exactly a good game, I had a lot of fun with Heroes of Annihilated Empires and enjoyed it even though parts of it can be difficult or clunky and I couldn't even finish it. It was kind of like high fantasy RPG RTS.