Wobin, you read my mind with the split-colored spade. It's simple and distinct with a known colortheme. I guess there needs to be a decision as to what the icon should symbolize; emphasis on the new version three (3) or the general Ace framework.
... ... Yeah, at 12x12 you have to start using pixel fonts to be able to see anything at all. I think it might be wiser to just use an icon that doesnt include text at all, just a distinct shape like the spade and some color combination.