How to play KNOCK card game

About KNOCK, from BoardGameGeek:

KNOCK is a fast-paced, mind-bending card game of memory, risk, and deception. Beneath its simple setup lies a battle of wits where players must bluff, guess, and outsmart their opponents without ever truly knowing what's in their own hand. Every move is a gamble - trust your instincts, read your rivals, and time your final “Knock” just right. Gameplay: Each player begins with four facedown cards they can't see. On every turn, players draw and discard cards to lower the total value of their hand which could go as low as minus 6 - but the twist is that most actions rely on limited information and sharp memory. Special power cards let you peek, penalty, swap, or reveal cards, creating chaos and strategy as players try to piece together what's hidden. Timing and observation are key - one wrong discard or forgotten card can turn the game around. Goal: The round ends when someone boldly decides to “Knock,” freezing their hand and challenging everyone else for the lowest score. When the final turn comes back around, all hands are revealed - and the player with the lowest total value wins. Essence: KNOCK blends memory, strategy, and daring into one quick, competitive experience. It's easy to learn, unpredictable to master, and guaranteed to keep players guessing until the very last reveal. -description from the designer