In a recent Gamasutra article, Phillip Goetz analyzes strategy-based game interfaces. This wouldn’t be of interest normally, but the approach he takes, talking about metrics of number of steps to accomplish player goals is.
Goetz is talking about how you have to give orders to every ‘unit’ (a game element such as a factory or a squad), but in real life as you have greater responsibility you get greater authority and delegate on the one hand, and you have templates of behavior you can request. The point being, that our goals shift and we look for ways to automate tasks we’ve mastered and have to perform a lot.
The take home I want to suggest is that analyzing tasks and minimizing the steps to accomplish the users goals has been elegantly discussed in Don Norman’s 7 Stages of Action model (from his Design of Everyday Things), and this application is an excellent case study. He also talks about tools to measure things like learner actions so you can map what the user is trying to do to the number of steps to accomplish this.
There’s more (and it gets into the weeds a bit about objects), but this is a great start. Usability is part of learning game design (and learning technology in general), and good examples are one of the great ways to get a handle on it.