Space Based Game Possible with TGEA?

#1 You don't need a terrainblock at all unless your using terrain. There are a few projects under construction that are space games. I don't think any space games have actually been finished to my knowledge, though I could be wrong. It's certainly possible, but you'd have to be prepared to do a number of source code modifications.

There is an old thread on the TGE forums where the author went through most of the major hurdles and posted resource links or code to get people started.

#2 When taking the terrain out (deleting) through the editor the game will sometimes crash. To get around that if that happens just open up your mission file in a text editor and remove the terrain block by hand.

There are various gravity resources to be found here. Try 'em out and see which one works best for you.

A skysphere looks wonderful. A discerning eye can easily tell that your skybox is a cube when you're simulating space backgrounds.

This series of blogs is a good start for some tips towards a space game. You may also want to check out some of the discussions & blogs by James Laker (Burning) -- I've seen his name more often than anyone else in regards to a space game.

#3 Are these uable in TGEA?
Are the TGE resources interchangable?

#4 @Carl: those resources mentioned were for TGE, though it is technically possible to use them in TGEa with a little porting know-how -- it's a good learning experience. Something like one of the gravity resources should/will drop right in with very minor, if any, modification, but the SkySphere resource will take some extra attention because of the differences in rendering between the two engines.

For further reading info, and inspiration check out Bill Vee's blog series. His Atlas Spheres and accompanying gravity effect is awesome!