I can't offer a game with a narrative storyline, but the Chaotic Dreams team (creators of the Chaos mod for Quake 2 and UT series) is looking for contributors.
Since UT4 was abandoned by Epic we had to jump ship to the full UE4, which means we now have to make a full Chaos game with a variety of play modes.
This has put us back a long way and things are slow with a small group but we have been chugging along.