I played X-Com I again today (on the hardest difficulty level, losing a squad of eight to Sectoid fire
Anyways, I realized how similar EaW's base building system is to X-Com's system: You have a base that you "build extensions to", and which "takes part in battle and can be damaged".
So I thought I'd contribute with this. This is, according to myself, a good idea on what to expect:
Of course it won't have the same facilities, etc., but it's the same basic idea.
Maybe the graphics will be slightly better...