The Cerebral Assassin/The Game gimmick and being an ass kicker isn't really all that different, though I guess there does lie some sort of difference. Being the Cerebral Assassin implies being smarter in the ring and able to outwit other wrestlers and utilize your strengths and hone in on their weaknesses to defeat them, regardless of who they are or what their size is. Owen Hart was actually considered for this gimmick and nickname first, so I think it could be given to Daniel Bryan if he goes a more serious route one of these days. (But even this isn't the most unique of gimmicks, since just anyone could mention this sort of stuff in promos. I guess the uniqueness all lies in the nickname.)
As for being a big ass kicker, that's not really a unique gimmick or anything. There's been several bad ass gimmicks, though they may come in slightly different forms. You could just as well use Undertaker's American Bad Ass gimmick as an example. And speaking of which, since Goldberg was brought up, I always thought if Goldberg had a different persona of sorts, he really could have used the American Bad Ass gimmick. The nickname, the leather jacket, the glasses (sometimes) and the motorcycle.