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.

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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)

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