Let me start off by saying I love the Command and Conquer series. My favorite is probably Red Alert 2 with Generals trailing a little. The reason I like these games is for the Skirmish modes because i love to build bases. I tried out the Star Craft series but it didn't seem like a good base building game as the attacks came so quickly. So I am thinking maybe a tower defense game is a better fit. Can anyone suggest a good Tower Defense / strategy game that allows you to build a good base as well as defend/attack the enemy?? I prefer to play this on the PC so PC suggestions only please.
Yeah. I haven't seen too many TD games that focus on base building. I guess you might be able to say Orc's Must Die would fit that bill, but you are building mostly traps to take out enemies, not buildings.
As for strategy games though, check out the Civilization series. That is a series that is all about the base building, and you can actually go through that game without going to war and still win. Plus it is turn based, so you can take your time and not have to worry about some base unit raping you in the opening moments of the campaign.
Edit: I have to give a shout out to Gemcraft: Legends on Armor Games. As someone who plays pretty much every TD game that comes out, this is still my favorite. When it comes to depth of game play, no tower defense game comes close to this.
Edit #2: I agree with @Spoonman671: Sins of a Solar Empire is an incredible game that is worth your time. You might be better off picking that up than Civ, but it really comes down to whether you enjoy Space or Earth.
I love Orcs Must Die (even though I have little to no interest in most tower defense stuff) because you don't even need defenses/a base to be effective against the hordes. (although you do need them if you want to 5 star everything past the first act)
and it seems I might've misread what you were looking for there but aw well.
@lil_cheeks: I'm sure you know about it, and it doesn't seem to satisfy all your needs, but Stronghold is a game that is literally all about building a functional stronghold or fortress or castle or whatever. It's pretty awesome if a bit antiquated. Also a game that is in a similar vein is Majesty: The Fantasy Kingdom Sim. You basically are the King, you tell dudes what to build and they do it, it's pretty different from most games as you don't really have any direct control over your dudes, you can really only suggest. I know both of these are medieval games and you seem to prefer the sci fi games, and for that I'm sorry, but these are worth checking out.
I grew out of base building so I don't know any good titles off the top of my head other than starcraft but there are some new titles coming out on steam under the strategy section like Oil Rush. I've never played it due to lack of funds but I heard alright things.