Projecto de Game Maker 8.1 (as for numbering 8.1 vs 8,1: see note below)
Projecto de ENIGMA
Game Maker (Versão desconhecida)
Desconhecida=unknown (female form, since version is a female noun in portuguese)
Also, there's a new thing in portuguese called the "Novo acordo ortográfico" that means the spelling of words has been recently changed. I'm a bit outdated but "Projecto" might not have a "c" these days. Other than that, this should be fine and, in fact, most people will accept and perhaps even prefer the word with the "c".
As for the numbering, in portuguese the typical way to have the decimal separator is the ",". However, when it comes to software, I don't think I have ever seen the "," used. For instance, the download page for Firefox in portuguese uses a dot(.) for numbering.
EDIT: It is worth noting that the french version of Firefox(http://europe.mozilla.org/fr/
) ALSO uses the dot(.) for numbering