It's only "easy" to get to the space stage if you are on Easy difficulty. Normal is a completely new ballpark, in my opinion. I haven't tried Hard yet, but I am going to once I get my rank up to Onicient on my current game... I'm at Admiral right now... gonna be a while. >.>;
Also, to answer ThunderThylacine's concern, the only part of the game that really plays like Civilization is the stage of the same name and SIm City aspects are very few and not all that big of a deal in space stage.
Here's a run-down... Cell plays like a single player adventure where you swim around, eat, fend off predators, and evolve. Creature plays like an MMO style single player RPG where your creature parts give you stats and you can either befriend a different species and add them to your pack or hunt them down and have them for dinner. Tribal stage is like a simple RTS kind of like Warcraft where you either ally with or fight other tribes. Civilization stage plays almost exactly like the Civilization games. You start a nation and you ally with other nations or go to war with them. The ultimate goal of that stage is to attain total global dominance through whatever means you choose. Finally, space stage is an accumulation of all you have done so far. You can expand your empire by setting up colonies and terraforming planets and set up relations with other empires by, again, either allying and trading with, or going to war with them. You can also be an explorer and search the universe for artifacts and undiscovered systems. The ultimate goal of that path would obviously be finding Earth among the literally thousands of planets in the game.
I am currently exploring and setting up relations with other empires as I go along. I have set up some trade routes with the Shaell Empire and, once I get the money, I plan on buying one of their systems, which is an option if a trade route becomes successful enough. I've found I think around 500 star systems and I still have only found maybe a good 3% of the total universe in the game. It's staggeringly huge...