METAL MARINES / Namco / SNES
Here's an interesting futuristic RTS from Namco ... I think Dune 2 predates it by about a year, but it's one of the earlier examples of the genre.
Yeah, but it's pretty different from the usual RTS. In fact, it has a style that I really haven't seen emulated in any other games that came after it.
The setting is some futuristic world where some goofy anime Evil Empire has taken over everything ... there's not a whole lot left to take over though, it looks like a good 60% of the planet wound up underwater.
Al Gore tried to warn you!
The whole underwater thing is just a plot device to facilitate the game's mechanics - each map has you and the enemy on separate islands. You lob missiles at each other, and also deploy the titular Metal Marines to wreak havok on the ground.
While doing that, you have to beef up your own defenses with anti-air missiles and gun pods. You also can build structures that accelerate your money production (used to build new units) and your energy production (used to launch attacks).
There's a limit to how many overall structures you can have though, so you have to strike a balance.
It's pretty fun, has good music and the cinematics in between levels (and the enemy commanders always calling you up to deliver random taunts) are fun.
The only problem is that the gameplay doesn't really change at all over the course of the maps. It gets harder, but there's no gradual introduction of new units and new challenges like you have with games like Warcraft and Starcraft. Once you've played the first map, you've seen the whole game basically.