I think that Stardock should stress the adventure game aspects, which sounds like that would include their "post game DLC" plans as well, and the love for SC as a unique "Adventure-Arcade" game that many of the original generation of computer gamers have for SC2. SC2 really was one of only a few games of that era that was held up alongside of Civilization and Master of Orion at the time, and is still remembered that way by that generation today. This should be the focus of the message they want to get out there. The unique, one of a kind, adventure game it is the way it blames adventure genre with "mini-arcade games". Then, with the focus really on the unique adventure game that was so beloved by the original generation of computer gamers, show brief glimpses of the two arcade elements, lander and space combat, without really discussing them. Intentionally leave those aspects kind of mysterious. That is what I would do.
The reason why is that it seems too me like a majority of modern gamers have a negative impression of most arcade like games, especially top down space combat, because they see Space Invaders and Asteroids when they hear that. And they think of those graphics and sounds, and they don't want to play that in 2016. I would try to make arcade aspects as "mysterious" as possible, and let them be intrigued by what little they see of the lander and space combat. Make that something that makes them want to try the game just to see exactly how those brief scenes they saw tie into an adventure game, and one that was so beloved by its generation.
I think that, especially with the space combat, the more you show and the more you say... the more you lose anyone under 30 or so.
But once they try it... the space combat is exactly what will draw such a large crowd too it. My opinion is biased, of course, since I have been certain for over 20 years now that top down space combat is "the lost genre" of computer games that would still today be second only to FPS shooters in online popularity. It's got everything for that, and more in many ways than FPS. Especially the ability to jump in for 5 minutes and then leave without anyone even noticing, much less caring (this is, I have always felt, the primary reason FPS games are dominant as online games). But even single player, if they play the space combat there is a large audience out there who will be deeply drawn into it. It's one of the original three big genre's of modern games... Advanced Squad Leader (RTS), Star Fleet Battles (top down space shooter), and Dungeons & Dragons (RPG).
Don't tell them about it, because then they won't like it. Just let them experience it, through an adventure game even!!! If you build it, they will come:-)