Zero 21

🎮 How to Play

Welcome to Zero 21! The goal is to keep your cumulative card total between 0 and 21. You start at zero. Each turn, you will be dealt a new card with a positive or negative value. You must choose to either ADD or SUBTRACT this card's value from your running total. Your choice is pivotal! If your total ever drops below 0 or climbs above 21, the game is over. This card game demands careful calculation and quick thinking to survive as long as possible and achieve a high score.

🕹️ Controls

Zero 21 is designed for simple, intuitive play across all devices.

• Primary Controls: Use your mouse or finger to tap/click on the two large, on-screen buttons: the green "ADD [+]" button or the red "SUBTRACT [-]" button to make your choice for each card.
• Desktop/Keyboard: For faster gameplay, use the LEFT ARROW key to subtract the card's value and the RIGHT ARROW key to add it.
• Mobile/Touchscreen: The game is fully optimized for touchscreens. Simply tap the desired button on your screen to submit your decision. The controls are effortless and provide a relaxing experience.

🎯 Objectives

Your primary objective in this mentally stimulating card game is to survive by keeping your total within the 0-21 range for as long as possible. Each card you successfully play increases your score. The long-term goal is to beat your personal high score and climb the leaderboards. Victory is achieved through strategic balancing, making smart choices with each new card, and resisting the temptation to push your luck too far for a higher, but riskier, total.

💡 Pro Tips

Master the balance of Zero 21 with these strategic tips to boost your score and gameplay efficiency.

• 🎪 Always calculate the outcome for both adding and subtracting before making your move. This quick mental math is the key to longevity.
• ⚡ Use the keyboard shortcuts! The left and right arrow keys are much faster than clicking, allowing you to maintain a good pace and rhythm.
• 💰 Manage your risk. If your total is near 0, be more aggressive with positive cards. If you are near 21, use negative cards to create a safety buffer. Staying in the middle (around 10-11) is often safest.
• 🏆 Practice makes perfect. There is no substitute for experience. Play multiple rounds to learn the probabilities and refine your instinct for when to play it safe and when to push the limits.