Sounds like a fun challenge. Start by picking a core mechanic that can stack layers—like building a grid where each tile unlocks a new rule. Keep the win condition clear but reachable only by exploiting patterns you only notice after a few rounds. Test early, look for hidden symmetries, and tighten any loopholes that let people win too easily. Remember, the best puzzles feel like a secret handshake—easy enough to learn, hard enough to master.