[Taqwus]

a) LC vs Space Station -- An LC, if memory serves, is 400kt -- almost as heavy as your Station. It's also harder to hit. Plus, if the LC had decent armor, that could more than balance your shields given that your weapons aren't armor-piercing. IIRC, even the first level of armor can absorb 50kt per 20kt space. You don't mention the LC configuration, which is more than slightly important here.
b) Damaged by a colony ship -- the AI is, occasionally, smart enough to ram in tactical combat when it's doomed. It happens very very rarely as far as I can tell, but it does happen every once in a great while.
c) 100 turns is more than enough to crush your opponents -- if they're AI anyway. With a 3-planet high-resource/high race point start, and the non-optimal combo of Psychic/Time, large galaxy (and other settings default), I've crushed my foes to the tune of ~1.5 million pts in 60 turns. It was more than skirmishing, to the point where some of my planets were annoyed with me because of the number of civillians I'd wiped out ('peaceful' population, heh, just to make it more interesting).

Sure, you won't be able to explore the whole tech tree -- which means you've got to make choices. But if you want to go beserk and end up with colonies in almost every colonizable system, you can -- the default-level AI in the demo isn't strong enough to hold you to "skirmishes".

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-- The thing that goes bump in the night