Google has clarified in its software application schema help document that VideoGame is not a valid node type for Software Apps. If you want to use VideoGame, you can, but you must also include another supported type for your structured data for software apps to be supported.
Google wrote "Google doesn't show a rich result for Software Apps that only have the VideoGame type. To make sure that your Software App is eligible for display as a rich result, co-type the VideoGame type with another type."
Google listed this example, showing 'MobileApplication' as the supported co-type:
So keep in mind, if you are looking to have software app schema that works as rich results in Google Search, do not just use the VideoGame type.
Forum discussion at Twitter.
