[deepthaw]

Firefox blocks this domain. So I overrode it. Then my employer's network blocked it. :(

[inanutshellus]

Same. Firefox says it's got a bad cert, and employer detects it as a malware site. Wonder why. Certainly it doesn't block all of github.io... why this guy's site?

[antod]

Firefox on Ubuntu isn't showing any warnings or errors for me.

[SushiHippie]

Maybe it got flagged as a "game".