Pedro Martínez: Correct me if I'm wrong but aren't there different colors for pro-5-in-line and bb+? And small fast esp is easily recognized by the lack of vulcans ;)

Gordon Shumway: For Battleboats plus, and dark battleboats, there's a different board color, i can assure that

Gordon Shumway: Oh, you're right...:) I just don't pay attention to the colors. It's way easier to look at the name of the game than remember all the colors...

Pedro Martínez: You're right about the remembering - I don't remember any color, but the fact alone that the board is of a different color makes me aware that I am not playing the default variant. And the fact that every chess variant is of a different color makes my brain - which is kind of lazy - believe that I am playing normal chess if there is no border. This doesn't mean that I won't notice it at all - but at least the chances are very much higher that I'll ignore the name of the game.

And Extinction Chess is a special case I think. In most variants either the possible moves are different - as in BB+ - or the effect of them is not of any difference - as in Pro Five-in-Line. While in E.C. a normally not-so-bad move could make you lose the game without further notice.