Personally I’d revive Begone (Nplay.com). It was an FPS game built on Unity engine. I would to play it one more time just to feel the GUI, the servers and the community again. They had cool account systems and forums aswell.
Honourable mentions:
Minibash (a spin-off game to the game Toribash)
Fly like a bird 3 (gamevial.com)
And Attack on titan tribute game(Feng Lee)
Bloody Roar
It was a 3D fighting game in which the fighters transformed into animal hydrids, like a werewolf. It was initially published by Konami and developed by Hudson Soft, but the series stopped in 2003-2004, and a 5th game was planned until cancelled in 2022.
In an era where fighting games like Street Fighter, Tekken, Mortal Kombat, The King of Fighters and Guilty Gear were revived, a returning contender would have been welcomed ^_^
These days, consoles can also manage the transformations easier, in addition of adding more animals to the roster.