Good news: it looks like Choice of Games has managed to sort out all of the problems relating to the Steam release, and now both Guns of Infinity and its immediate predecessor Sabres of Infinity are available for purchase on Steam!
You can take a look at the Steam pages for both Guns of Infinity and Sabres of Infinity here.
Paul Wang 
April 1st, 2016 at 5:23 pm
Mr Wang,
I am rather glad to see that the wait for this malarkey has been vindicated (and hopeful that I wont have to wait too long for the culmination of the bloody affair), – and with such marvellous care and detail, at that. I mean, it should go without saying: Although well meaning (as pretty much everyone’s are), your socio-political views and sentiments are completely abhorrent and reprehensible; It is refreshing to see that, nonetheless, you are capable of describing a much more virile period of history (relative to our current, dissolute standards) with such finesse. Intellect and devotion, doubtless, have served you well; Likewise, your shameful inclination, when viewing such a time, have probably given you the disdainful cynicism necessary to describe it reasonably: St Boethius did note of the capacity for evil to produce good, after all.
Nonetheless, a thorough congratulations are in order. It was a magnificent game, and I have recommended it energetically. I especially liked that I was somehow able to be knighted, become a major, and still not have a single medal. Curious, no?
Congratulations, also, on the marriage.
Kindest regards, etc.