The ability to find tech if you capture enemy worlds largely intact is the saving grace of the game. That is what allows you to stand a chance when playing from a hole, and the most beautiful part is that luck has nothing to do with it. Not a thing. No thing. Nothing. If you manage to plan and carry out a successful invasion of an intact world of a more advanced enemy, that's strategy. THAT is real strategy, not these dice-flippin wannabe games that call themselves "strategy". You need enough elements to be able to mount a successful invasion, though, and that's no walk in the park. You need to be able to defeat (or get past) enemy defense bases. You need to be able to deal with enemy fleets well enough. You need enough ground combat tech to be able to win when you land. You can't fall too far behind in tech or your own defenses will be disarmed (useless) and you'll be steamrolled. And against a truly dominant opponent, you'll have to find a chink in their armor, to correctly identify and target a weaker world that you can overtake, WITHOUT leveling it in the process. It's not enough to destroy a world, or to take it. You must take it largely intact to steal tech from it, and that requires precision.
There's a lot more to the game than I can say in one paragraph, but that is the keystone, the piece that holds all the rest together. If you still haven't checked out my site, what are you waiting for?