@Schaulustiger

The galactic gardener thing was actually one of my favourite elements about it. You could gain tools over time that would allow you to wildly terraform planets if you had the resources, and occasionally you'd come across these semi-rare cubeworlds (I think I came across five or so when I was playing). I made it my duty to make every one of those cubeworlds a garden of eden, with amazing wonders for all to see.

Also, making it to the centre of the galaxy and meeting the greatest intelligence of the Universe is, hands down, one of the best moments of the game. Really, don't spoil yourself on that if you can avoid it, since it's really worth working toward.

@Xocrates

I never tried blowing up Earth! You can do that?! I wish I'd thought of trying that, but I made it a point to colonise Earth. Anyway, I agree with what you said, and whilst the elements of the game aren't complex, I don't think they're shallow per se, and it's really about getting as much out of them as what you put in. It can be really fun to see your creatures interacting with others. And it's even moreso if you create a catalogue of your favourite creature makers, so that you see primarily their creations in your galaxy.

I think the thing to keep in mind with a game like this is that there are other, more complex, and meaty games out there, many more, and it doesn't hurt for this to exist, or for one to play it. It's not something you play for extended periods, but it's something you play when you just feel like having a little fun. It's all about that, really, it's a toy. It's a toy in the best meaning of the word. If one stops thinking of Spore as a game, and thinks of it more like a really awesome transformer, then it makes more sense.

As for the space part being 4X... that's a really good description! That's exactly what it is! I wish I'd thought of that. Yes, you're right. It's 4X done casual-style. But then, it becomes so much more than that if you get the space adventures pack, so much more. Still, I won't spoil that for Schaulustiger too much by revealing everything, but... I will link this.

http://www.youtube.com/watch?v=ex_Si79O9Ys

(It's entertainingly WTF, but that's Spore for you.)

Oh, and I mentioned mods, right?

http://www.xspore.com/custom_content/3387_spore-modifications.html

There you go. I haven't played Spore in a while so I'm not up on current mods, but reading over its description, I'd say that BetterSpore sounds like a damned good catch-all for all interests.