correction, i've also built organic levels in max from splines. it's a bit janky but fun... build out the floor of your map with splines convert to edit poly then teselate... then extrude splines out to make the organic walls... this is useful technique for doing organic hallways in general...
if you're creating this level in a modern engine, you're going to probably want to do it modularly or somewhat modularly. I generally design spaces using lego pieces (and i do the same with organic stuff) build out the tunnels as re-usable tunnel pieces... and change the props and lighting in the tunnel to make it look…