1.
Before you die, click 'retry stage' to restart the stage without losing your items.
By combining the 'very easy' difficulty level with this trick, the game will become literally very easy.

2.
Hammer: damage 1
Knife: damage 2
Boomerang: damage 1 + 1

Because the types of items that can be placed in the inventory are limited, assuming that you don't lose your items, the knife is the most effective.

1) Play Before The Night
You can't miss it. Just run the game.

2, 3) Fluffy Lover&Fluffy Killer
Give Fluffy a carrot and kill him.
★ Offer Fluffy a carrot before putting an end to his life.

4) Meat Party (Missable)
Collect 20 pieces of meat in your inventory and scatter them on the ground to commence the party. If you kill animals, you can obtain meat which can be stored in your inventory. However, it's important to note that if you die, the items in your inventory will disappear.

5) Schrödinger (Missable)
Put 10 cats in a box and showcase them.

If you progress a little further in the stage where cats appear, you can obtain a box. Use the box on a cat to obtain the 'Cat in a Box' item. If you store 10 of these in your inventory and scatter them on ground, you will get the achievement.
★ Cat in a box should not be exchanged or used just in case.

6) Thank you!
Clear the game. You can't miss it if you don't give up.

7) A Masochist
Die 50 times.