Wow, so many posts from Germans and not one of you realizes that ß is simply a small letter that has no capital letter equivalent. Thus, words with an "ß" are written with "SS" when written completely in caps. The only exceptions are family names, where the ß is kept for caps to indicate the spelling, and Swiss people, who don't use the ß at all and write everything with "ss" instead. Also, writing "ss" instead of "ß" is applicable when the person typing it is unable to use that character (or just can't be bothered) - just like with "oe" instead of "ö". I doubt that any of the mods who post new releases here has a keyboard with a "ß" key.
Setzen, Sechs! Back to school with you, and leave your flashcarts at home.
The game's logo is all caps, as you might notice (see those "E"?), so naturally they didn't type "WEIßE" which would look utterly retarded regardless of what font they would use because it's a mix of small and capital letters. And as a side effect the logo doesn't look awkward to Swiss customers.