This is an astonishingly good game; probably the best open-source game ever made (not counting games which published their source many years after losing relevance). There's a keen game-design sensibility and attention to detail here which is very rare, let alone in an open-source project. It's an elegant, tight combination of ideas from Factorio and the tower-defense genre that feels very much unlike either of those two inspirations. It's very satisfying and addictive to tend to your growing garden of production lines and defenses while layering more and more complexity as technologies and space allows. I hope you make a fair income from the Steam release!