Cell Stage was good fun, very imaginative gameplay, and it's the only stage where the placement of your weapons actually matters. You need to turn on your side and whatnot to attack or eat or whatever you need to do. Where as later on you just click to attack or whatever and your creature will work out what to do.
Oh, and its worth noting I've played up to early Space Stage with two different races; A super-evil nazi militarist regime and a super-happy pacifist herbivore race. Interestingly, it's easier at first to just be a evil carnivore and kill everything but around the tribal stage all the way through to the space stage being a war warmongering bastard becomes really hard.
Creature stage plays out like World Of Warcraft. That doesn't mean you grind constantly, just that the controls are similar (Especially combat) and that you spend long amounts of time walking from point A to point B. But, there aren't any epic mounts. Anywho, this stage is great fun for both parties. As a herbivore I ran round eating fruit and making tons of friends that would come on long adventures with me. As a carnivore I only grouped up with my own race and made extinct all other races, with my big stabby claws. I even killed children and ate eggs, it's pretty messed up. Anyway, nothing shocking really, plays just as expected.
Tribal stage is pretty frustrating. It's an extremely shallow small-scale RTS, but the distances you travel to either convert or burn down enemy villiages is very long so if you so much as leave your base for 1 minute you have tons of little critters stealing your food and burning down your huts. It's not that much of a big deal though, it's very positive and fun to play peacefully and give every gifts and make friends through dance. Killing everyone is considerably harder, and you may end up relying on luck. Oh hey the green tribe was entirely wiped out by an epic monster, good chance to go raid their hut..
Civilization stage plays nothing like Civilization. There's no scientific discoveries, no transports (which makes ground vehicles pretty much useful) and the most disappointing thing about the shallow gameplay is that you can only have 3 vehicles. One air, one ground and one water. You can build multiple ones of course, but there are only three units to build. You make it in your lil' unit builder and that's it, thats the unit you have. If you design another one, all the units of that type automatically change to the new unit. Who wants to play an RTS with 3 different units? There's very little difference between being peaceful and warring here, the military path has to blow cities up and build up from their ruins whereas the religious units convert the city and get to keep all the buildings. In fact, it's a lot easier as a "religious" nation and plays the same way really. You just have speakers in stead of guns. And these speakers can blow up tanks. Anyway, you play through Civ Stage with your 3 units and win pretty easily, nothing amazing, nothing deep, very mundane. In fact, it's the only 3D RTS I know of that's shallower than Empire At War. Also, it would've been far better and more tactical if it was turn based. So, forget this dull stage and onto the space stage.
Space stage is frustrating. That's an accurate description. The original view of the space stage Will Wright presented us with in 2005 was that it would be a relaxing wander through space looking for small, rare civilizations and pretty stars... But it's nothing like that. The moment you escape your planet you're surrounded by competitive aliens with huge empires hundreds of times stronger than you. This makes it really difficult to start off. When I was playing as a military race, I attacked and pissed off the first race I met. it turns out, when you're on the map screen you can see where other races empires stretch over, but only if they're either your ally or your enemy. Since he just became my enemy, I was able to realise my home planet was right in the middle of this alien's territory. Before long it was impossible for me to leave my solar system without incurring massive damage, which you can't fix without heading home. And my home planet was under attack every 5 minutes.
Okay, so it's much more fun as a peaceful nation. I got to fly around in my lil' ball space ship making friends with alien races, forming strong alliances and trade routes. Well, it turns out those "alliances" are worth ****. See, I had this nifty little planet I'd set up a colony on. My first colony! It was growing well and I'd become pretty attached to it, since all my income came from it and the guy on the planet would always give me a warm greeting when I turned up to pick up some materials or whatever. Anywho, all my trade went through this outpost. One day I'm happily scooting around the galaxy doing some munial tasks for my stupid allies and two different races at the exact same time contact me- they both tell me to give them hundreds of thousands of monies or they'll destroy me.
Now, I haven't got this money. Never at ANY point in the game have I EVER had this ammount of money, not at any one time. There was nothing I could do to stop them, so they declared war on me. Suddenly, giant red rings appear round my solar system and I realise once again my home planet and my friendly lil' colony are inside their territory. Within a minute they're attacking my awesome colony, so I rushed over there to protect it! I even talked to my allies to see if I could get help and all I could get was one small, weak ship to join me. Oh well, I head over there to face them off and I'm met by three ships of equal size but far more power than mine. I get slaughtered and my friendly lil' colony is destroyed. I come back to life to find I once again can't leave my solar system without being attacked. There's absolutely nothing I can do to get my colony back because my enemies are just too strong and I'm no longer getting any income since that colony controlled all my trade routes.
So, I would describe space stage as at best annoying, and at worst perhaps even stressful. Which is the complete opposite of what a game SHOULD be, obviously.
Overall, it's a disappointment. The whole game should've been a lot better and deeper, but it was dumbed down and cut apart for the casual audience.