Having centralized authentication servers. Otherwise MS purchase of it wouldn’t kill the normal Skype, and by now it’d be probably, like ship of Theseus, actualized for modern security and other requirements. Like X-Wing Alliance and WoW and Warcraft III modding, and other iconic games getting even replacement engines.
Hotline got FOSS clients at some point, some still work, some people even make new ones.
Having centralized authentication servers. Otherwise MS purchase of it wouldn’t kill the normal Skype, and by now it’d be probably, like ship of Theseus, actualized for modern security and other requirements. Like X-Wing Alliance and WoW and Warcraft III modding, and other iconic games getting even replacement engines.
Hotline got FOSS clients at some point, some still work, some people even make new ones.