I don't understand this hobby. What's wrong with the original box art?
Well, I guess I'll take a whack at it.
The mysterious white patch in the corner of the front cover is distracting, even from the thumbnail.
The back cover looks pretty amateur as well, as I can see some text overlapping the screenshots.
The screenshots should have some border/and or shadow around them.
The readability isn't that great, since the picture gets dark around the middle area.
There's too much contrast in the background image.
I can't tell what those bullet points are supposed to be, but they certainly don't make things look better.
There is a strange blank space in the top left corner since the right corner is filled and all of the smaller text is left justified. I think you'd be better off left justifying the text at the very top.