I've yet to try C.A.R.D. Revolution. I "suppose" I can try the ROM if it works fine without internet access. I don't know if online functions of Dreamcast or GameCube games can work on emulators or not. Or if C.A.R.D. Revolution needs to be online to play.
But, sometimes I wonder why Sega hasn't made an "answer" to Pokémon TCG, as C.A.R.D. Revolution goes to show they could make a TCG if they wanted to.
May be because Phantasy Star Online Episode III: C.A.R.D. Revolution did not sell well so they abandon that kind of gameplay.
Right now the game's gameplay was appreciated and praised for solid and well-thought-out mechanics, but that's not the case when it was released.
Most PSO fans back then expected it still to be action RPG instead of a turn-based card game format.
Personally I love SEGA's trying to do something different but they're not supposedly naming a spin-off game into a sequel (Episode III).