Wow, this is so good, not my kind of game but it's really well done and the graphic style is incredible.
Also this kind of games it's usually popular on YT, have you thought about giving it for free to a few youtubers?
you could get a lot of attention in that way.
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Also code related question, if I can ask, you said that you are for the most part using sf::sprites, for the terrain too? doesn't that cause issues? or the culling is enough to avoid problems?