>I think that this offset (x, y) should be expressed in pixels from the top-left corner of the sprite as usual, not in tile times and tileh times as it's now.

I think once you slice a sprite sheet, you should only need to worry about the abstract coordinates.  Remember that it's not just the tile size, but also padding that you need to consider.

>Yes, you could specify tile size at sprite definition, but this would prevent you from using sprites with different tiles size in the same component. This is also the reason why I think that specify tile size at sprite definition less useful than specify it at reel creation.

You can call Crafty.sprite multiple times, to slice the same sprite in multiple sizes.  The advantage of what you're suggesting is to have multiple animations of different sizes on the same entity.  I'm not sure this is something we need to support directly.  (You could still do this by manually swapping out the underlying sprite component used.)

>Why would you want to specify arbitrary sequences of frames? This could be achieved by building a spritesheet following specific rules.

Imagine you had several animations that always had the same beginning and ending state; you don't want to duplicate the image each time.  You're right that you always *could* prepare the sprite sheet so that each animation is sequential, but that's not necessarily how people want to work, and it might be pretty inefficient.

And this doesn't add much complexity, since it maps pretty easily to the way things work on the backend.  It also lets people tweak the animation without rebuilding the art assets.