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4X is a genre of strategy-based games in which players control an empire and "eXplore, eXpand, eXploit, and eXterminate". Emphasis is placed upon economic and technological development, as well as a range of non-military routes to supremacy. Games can take a long time to complete since the amount of micromanagement needed to sustain an empire increases as the empire grows.

Pretty sure everything is indie on itch.io but just in case you want something extra indie.