Some of those listed games were third-party than Sega,
No no no, all of those games are published by SEGA (and Atlus).
None on the list are published by third party.
If they are developed by other companies,
it would meant the developer was second party since it's published by SEGA,
not third party.
If I include third party games like Mortal Kombat 1,2,3 on Genesis
Or KOF series, Street Fighter Alpha 1,2,3, Darkstalkers, and Marvel vs series on Saturn & Dreamcast
the list would be tenfold,
lot lot longer than right now.
... such as Power Instincts.
Power Instincts was Atlus games.
Now that Atlus is part of SEGA, Power Instincts became SEGA's franchise.
It became a first party game now.
And Guilty Gear was the step-child that was reluctantly included in the marriage and cut ties at X2.
Arcade version of Guilty Gear series are all published by SEGA.
Arcade games being published by SEGA in Japan gave it more visibility since SEGA used to have hundred of arcade centers.
Even when Nintendo want to publish arcade games they chose SEGA (Luigi's Mansion, Rhythm Heaven, Pokemon Corogarena).
Burning Rivals is ugly, but still Sega.
https://www.youtube.com/watch?v=-N0yXGVWS1Y
Yeah, but remember when SEGA release mini arcade with built-in arcade games?
It didn't include Burning Rabger.
It include Dark Edge instead.
Now that's a SEGA fighting game that I could enjoy.
The reason why there were few VS fighting games from SEGA is because SEGA of Japan always rejected all ideas of it after Virtua Fighter was released.
Eternal Champions was planned to be trilogy with Eternal Champions: The Final Chapter should have been published by SEGA of America for Sega Saturn.
But the game was forcefully canceled by Sega of Japan, seeing the game as competition for the Saturn version of Virtua Fighter.