I got into Skullgirls because it was the first even halfway-decent fighting game with a native Linux port. Still playing it nearly a decade later because it's that damn good.
I also love Them's Fightin' Herds for being the next game to get a port. But with the current state of the game I haven't been grinding as much lately since I can't always hop on and get matches very easily... It's always gonna hold a special place in my heart and I will keep entering majors whenever it's there, but I've accepted its fate...
I've also been hooked on UNI2 as of late. I bought the Switch version since I have neither Windows nor PS4, but we've got an active Discord and biweekly bracket at least. I only know about half the matchups in the game though, so I'm at risk of getting caught out at majors.