I found out about it through osu!STD, and actually started out with osu!STD as my orig. gamemode. After playing RoBeats on and off for 2 years I got addicted to osu!mania and have been playing it for 5 months now.
got bored of standard for a while then i saw jhlee's ascension to heaven dt video later on and it just blew my mind on how inhuman it is. that's how i got into mania