In a nutshell, Galciv 3 can be described as Galciv 2.5 with prettier graphics with the tagline"does little that hasn't been done better elsewhere". And "Half Baked"
- no espionage system
- no ground combat
- space combat is completely hands off
-exploration is dull with small meaningless buffs or credit/research bonuses, or ship finds that add little to your empire (see Distant Worlds for how well this can be done)
-making important decisions on building construction is made less important due to the planetary economy slider. No need to specialize planets. Put all buildings down and change the slider around between economy, ship building and research at whim.
- Space combat itself is a excruciatingly over-simplified where both sides get an equal opportunity turn. No where in any games is there anything like this. When a unit A shoots Unit Bs health all the way to zero, Unit B should be dead and not allowed another shot back. Not other turn based games do this, and for obvious reason. It makes no sense!
My game consisted of clicking on shipyards to churn out constructors to construct and improve upon space stations. It was as exciting as watching paint dry.
Conquest - I barely conquered half a hostile empire's planets before they capitulated and surrendered all their stuff to me. And I was playing on Normal difficulty.
No ground combat to speak of. Damaged ships only had damage to HP, In other 4x your engines, weapons, other modules may be rendered inoperative -- creating a more strategic/tactical gameplay (stardrive, stardrive 2). Distant Worlds has huge distances where fuel (and a fuel refinery ship) for fast travel becomes a necessity.
In a nutshell, Galc Civ 3 while it may be great for its diehard fans, it also disappoints in innovation and lack of a lot of other 4x features found in other 4x games -- making it only viable for a select number of 4x gamers with that specific acquired taste.