Before diving into online battles, brushing up on the core gameplay is crucial. Uno Online utilizes the standard UNO deck with four colors (red, green, blue, yellow) and numbers ranging from 0 to 9. Each color has two of each number, along with special cards like Skip, Reverse, Draw Two, and Wild.

The objective is simple: be the first player to discard your entire hand. You can play a card if it matches the color or number of the card on the discard pile. Special cards add strategic twists. Skip forces the next player to miss their turn, Reverse changes the playing direction, Draw Two makes the next player draw two cards, and Wild allows you to change the current color. Don't forget the most iconic rule – when you have one card left, you must yell "UNO!" or face a penalty of drawing two cards.