Apparently they were demoing it on PC at E3 judges week, and it had prompts for keyboard and mouse. Phil Spencer later said there were no plans and it was just a dev build and they weren't planning it right now, tho he also said there was "no rule against it". But I don't see why they would add the PC prompts (which dynamically switched to controller prompts, and that actually requires implementation work) to the build if they weren't thinking of porting it to PC at some point.
Wouldn't be surprised to see it turn up a few months later, like Fable Anniversary.
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