When you use your engine metaphor, with the made to run, doing work, etc, I'm inclined to think that what you're really looking at is the difference between an automatic and manual transmission. You want the engine to decide when to change gear and to do it for you.
not at all Gabe...
your analogy is very appropriate, as it'll help explain my point of view... your conclusions are wrong though, mostly because you failed to really look at the analog that you yourself presented...
in short, i just want the engine to have a transmission... i'll decide if it is to be a manual or an automatic... and i'll do the shifting myself...
that's the whole point of an engine... anything less, and you become the engine builder... or, in the analogy your present, you become the transmission designer... there is no engine there, you become the engine builder...
a game engine will already have a transmission available... the developer using that engine, will be free to decide what type of transmission... how many gears... and how and when it will shift gears...
anything less, and it's not an engine... just a collection of spare parts that an engine can be made out of... in the game engine context, a collection of libs that you put together to make an engine...
now some game engines do enforce a sort of restriction, like you said... Torque for example, is geared (no pun intended) towards fpsers... therefore, that transmission will most likely be an automatic by deafult, and you will have to go into the engine, and redesign it, so that you can have a simulation, or a RPG type transmission... but the transmission is already there... and that's what makes it a legit engine...
--Mike