Hey touchArcaders, cheers for the initial feedback! I'm one of the developers of the game so it's nice to hear a good reaction.
Some answers:
1) Does it autosave?
Yes. If you're in the middle of a mission and turn off the device it'll pause the game.
2) Play your own music?
Yep. The guy that made our music won't like it, but you can play your own if you want.
3) How does the multiplayer work? Pass and play? Wifi?
Two-player mode is simultaneous (i.e. not turn-based) and on the same device. It's more hectic that way.
4) There are 500 levels, how does the difficulty change? changing the location of the planets?
The AI is quite sophisticated. The different cultures play in individual styles, and each culture has several levels of skill. You'll find that the first levels are hard to lose, while I think I'm the only person (I know of) that can beat the toughest enemies.
I'll stick around so ask more questions if you want. I emailed arn about a review... anything else I can do? Oh yeah, some codes:
FFEJYPHHL9NP
4J49J3YETPKM
KMPYP6XPYXHH
YN3R9JRPRAXT
9WE6ANRRX4KK
First come first served, but if you post nice stuff I might hand out some more.