Thank you so much for playing and for the detailed feedback. Really glad you’re enjoying it!
A patch just went out today that addresses several of the issues/bugs you encountered.
Dark Aura: The boss does drop 20, and each of the Void Shade enemies that it spawns during the fight drop 1 dark aura as well. More Void Shade enemies can spawn in and near the void ring that surrounds the entire first stage of the map.
Because this is just a demo, there technically is nothing else to do yet after killing the main boss. You can reactivate the beacon with Dark Aura, but it doesn’t do anything yet.
Codex not registering items/monsters: Crafting and combat kills weren’t triggering codex entries, only pickups were. This has been fixed.
Map: The map is now 100% the first key item found in the chests. Plus it has a whole new UI to it. Unfortunately i have not tested if it fixes existing saves.
Codex pages: there are 4 and they should all be discoverable, in separate chests. Chests can now spawn in more biomes.
Patch notes: https://riccardogrin.itch.io/dissolution/devlog/1401489/improve-enemy-spawns-new-discoveries-world-polish