Dragon Commander is set a thousand years before the events of Divine Divinity, in the time of Maxos (if you are familiar with lore from Divinity 2), when magic and technology were at their peak.
In the Divine Divinity lore, imps were talented magicians and engineers. In Dragon Commander they focus much more on the latter aspect, for a mad scientist type approach to technology. I don't know if the game will attempt to explain the existence of things inspired by steam punk / diesel punk, other than it being a time of progress, with an eventual downfall (ie few advanced machines in the other Divinity games).
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