Because I have neither time nor talent - nor desire - to create my own game engine, and also knowing that a graphics engine is not equivalent to one, I'm using Torque3D to build Robot. Why Torque? Why not Unity or Unreal? For two very simple reasons: (1) Because I am familiar with Torque and TorqueScript, and (2) because the Torque community has built up an impressive set of middleware, minimizing my need to reinvent the wheel.
Two middleware toolsets that I plan to use are LogicKing's Game Mechanics Kit (GMK) and Filament Games' Yack Pack (YP). Like any middleware, these pieces only offer me a foundation to build from. Neither GMK or YP support the desired Reputation System. But I believe with minor modifications, they can. Besides, if I were just to put a bunch of pre-built pieces...where's the fun in that?
Because YP is an architecture and not a visual tool to build conversations, another tool will need to be used. Thankfully, Chat Mapper (CM) by Urban Brain Studios is just such a tool. A few months ago, I wrote an YP exporter for CM thinking that it would be entertaining to polish my C# skills. Now, to my delight, my previous fun has become productive for my new adventure. Furthermore, Urban Brain has been extremely responsive to user feature requests, such as a wizard for localization and multiple images per actor. Can't beat that kinda tool.
...This post sounds too much like a sales pitch.