if you have a spear or any mid-range weapon on your main hand, you can't approach NPCs by 1 block
Found and fixed the issue for the next build!
I think the Intrine Arm shouldn't be affected by your mutations since it's not a part of your body
It should be flagged as synthetic and external, and therefore not subject to mutations. I've had some similar issues with other flags not loading properly, so maybe this is related.
shouldn't some mutations, like claw, beck, horns, wings, dorsal fin, be able to be removed on the doctor?
Mutations can be powerful, so having ones that take up slots is a drawback. If you were able to go to the doctor and remove pieces you don't like, getting an optimal build would be much too easy, in my eyes.
...shouldn't you use the secondary hand when you reach a situation that the main hand can't attack while the secondary can?
This is a leftover from old code where you'd have one "Weapon" slot and an "Offhand" slot, with both providing different functions. Since I've moved over to a "hands" system, I still only check the "main" hand while moving. I can see the benefit of checking all available ones before moving too. I'll add it to the todo list.
I once found an Item called Butchery Guide, but nothing happened when I used It
Whoops, a leftover item. You get the butchery ability from Saira now.
Sometimes NPCs teleport through the map
I'm afraid I haven't seen this one. Could you provide an example?
it should disappear after using it rather than keep it on the inventory
Yup, you're right. Not sure why it isn't removing itself from your inventory.
quest to Kill Izasna when I had already killed him, making it impossible to kill him again. I think the game should keep track of the main NPCs killed
Yeah, that makes sense. It does keep track of important NPCs (like Isazna) that are killed already to prevent them from respawning under most circumstances. I'll just auto-complete the quest if that is the case. I put it on the list.