"Some of them are music games. Some of them are not full-on rhythm action games. Some of them are brand new things that we created from our guts and brains here at Harmonix. Some of them are sort of like things we're explaining the universe of." - John Drake, Director of Communications and Brand Management at Harmonix
While there are indeed music games in the works, it sounds like some of the other projects might not involve music at all. That's not very Harmonix-like!
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[Source: GoNintendo ]