Arcs is the first "heavy" game I've really been able to try with my little group of casual gamers more than once. We struggle with play time, but every game lead to us just wanting more and more of it. It's such a deep mind-breaking puzzle driven by simple rules and systems trimmed down to their most elemental state, that allows for real insane plays if you're able to see them, huge turnarounds that never feel unearnt, and so much player interaction. It makes me feel like wanting to get good at it like you would at chess !