Also known as a system an RPG’s engine is the set of mechanics the Guide and Players use to model or emulate the world of the setting. It lays out what is possible or impossible in a setting and is most often used to settle disputes and guide choices.
Each role playing guide –RPG– has a unique engine, to one degree or another, and some can be complicated while others are simple. As far as I’m concerned the matter is not that the engine appears realistic but gives realistic results. So the combat engine in Tunnels and Trolls is –to me– more realistic in it’s results than most any other combat system out there.
Now keep in mind that we’re not talking about a game of any sort, so you don’t need to fuss about play balance. All you really need to concern yourself with is that the engine you use doesn’t favor anyone to any degree, and that it is easier to understand and use. I have run across RPG engines that were just too hard to comprehend, so I don’t bother with trying to remember which ones they were. Speaking as an autistic, they were just too good at triggering a melt down. Melt downs are no fun.
So now that you know my position on RPG engines and how I understand them, we can go on to further entries in this series.