if you want to make a game similar to any example projects, Neoaxis can be a good choice. just make new graphics, tweak the codes a bit and release. maybe I'll alter the RTS game, and could be a good start... but this is also valid for Esenthel, but there are far fewer example projects, and some of them are for a little money (~40EUR), but they are probably the most effective way to get a working MMO solution. Unity also has nice open source projects. 3dgs not really, only small ones.

it would be a great improvement in 3dgs to officially integrate the Recast/Detour navigation mesh pathfinder similarly to Neoaxis, Esenthel, and as I remember it is also in Unity Pro. in Esenthel it is so easy to use! (but lacks character collision, maybe that should be solved by OpenSteer somehow...) WJBender should be paid by Conitec to complete his great plugins...