I have no idea what tacticsarena would use as I've never bothered to play it, but here's a bsaic sprite sheet:
http://board.flashkit.com/board/show...0&postcount=29

As you can see that's the same image just rotated, but in your case the sprite sheet would contain different frames of one type of animation along the x-axis, and in rows you could have a different type of animation (eg. first row contains shooting animation, second row contains walking animation, third row contains standoing animation ,etc.). Then your coder could create some simple code to tell the engine which part of the sheet should be visible (scrollRect() is pretty muh like a mask, only showing a 'window' of an image), based on which animation should be playing and what frame it is up to. Because you just need the one image as a bitmap, you should be saving memory ( i think).

I probably don't know enough about the subject, so you may want to do some research yourself on the subject or listen to the people on ths board that actually know what they're talking about.

Viza.