The term “alt-right” has been in use in the internet community by those who reject SJW leftism but don’t embrace neo-con Republicanism, or for that matter, “tradcon” Republicanism either. So, for example, a lot of the Gamergate folks, who worked to expose the bias and lies of traditional media, might consider themselves “alt-right”, mostly because they are fighting the media machine of the Left, but still don’t identify with, say, the Bush-style Republicanism or even Republicans at all. Another example is young men who feel demonized by left-wing rape hysteria and so troll the SJW rape-hype machine.
I’ve never heard the alt-Right term until today and have NEVER heard of “GAMERGATE” before and haven’t a clue about that.