Too much choice often interferes with learning; just like creating a simulated environment that is too real becomes counter-productive, especially with novices. Giving the learner too many things to think about too soon makes it much harder for them to navigate their way through to the destination you want them to find. There’s even a theory of choice overload: “The choice overload hypothesis states that an increase in the number of options to choose from may lead to adverse consequences such as a decrease in the motivation to choose or the satisfaction with the finally chosen option.” (Benjamin Scheibehenne, Rainer Greifeneder, & Peter M. Todd, 2010)
On the other hand, insufficient choice is also a problem. Clearly there is a sweet spot for how much choice to offer at any given moment, but I suspect the right amount will depend not only on what it is you are trying to teach, but also on who your learners are, and what they already know. Even worse, it is unlikely that your target audience will be uniform enough to allow you to set up exactly the right amount of choice in any serious game or other learning application.
Benjamin Scheibehenne, Rainer Greifeneder, & Peter M. Todd. (2010). Can There Ever Be Too Many Options? A Meta?Analytic Review of Choice Overload. Journal of Consumer Research, 37(3), 409-425.