The classic guessing game: narrow down the range using "too high" and "too low" hints, and find the number before you run out of guesses. Switch to 2-player mode to take turns — whoever guesses the secret number loses.
Score: 0Round 1
Range: 1 ~ 50
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Guesses left: 8 / 8
Ready? Click start to play!
💣 Ready?
Starting at 1~50 — find the number before you run out of guesses
Each guess gets a "too high" or "too low" hint — guessing the middle of the range each time (binary search) uses the fewest guesses
Best Score
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Highest Round
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Pick a range — the system secretly picks a number (neither player knows it). Take turns guessing; whoever guesses it loses.
🔴 Player 1's turn
Range: 1 ~ 100
Take a guess
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The duel mode doesn't score or rank — it's just about not being the one who guesses right
🏆 Number Bomb Leaderboard
The Origins of Number Bomb
Number Bomb (also known as the "Ultimate Password" game) is a classic number-guessing game popular at gatherings and in classrooms: one person secretly picks a number, and everyone else takes turns guessing, getting a "too high" or "too low" hint after each guess as the range keeps shrinking. Whoever guesses the secret number "hits the bomb." This version turns it into a solo defusal challenge you can play by yourself, while keeping the classic 2-player turn-based mode intact.
How the Guess Limit Is Designed
The number of guesses allowed in defuse mode isn't arbitrary — it's derived from the classic "binary search" algorithm. If you always guess the exact middle of the current range, a range of 1~50 is guaranteed solvable in 6 guesses or fewer, and 1~1000 in 10 guesses or fewer. This version adds 2 extra guesses as a buffer, keeping the limit fair while still leaving a bit of tension.
How to Play
Defuse mode: the screen shows the current number range. Enter a guess and press "Guess!" — the system tells you whether the answer is higher or lower than your guess, and you narrow the range accordingly. Your remaining guesses are shown as a burning fuse; if you run out before guessing correctly, the bomb explodes and the game ends, with your score based on total points earned. Guess correctly and you automatically move to the next round, with the range growing larger and the guess limit increasing accordingly. Duel mode: pick a range and press start — the system secretly picks a number, and two players take turns guessing (just hand off the same device). Each guess narrows the range further, until someone guesses correctly and "hits the bomb," losing the round.
Tips for a Higher Score
The most efficient strategy is to always guess the exact middle of the current range — this cuts the range in half with every guess, closing in on the answer with the fewest possible tries. Your score is based on the size of the range (bigger ranges give a higher base score) and how many guesses you saved (each guess saved adds bonus points). To score high, push through to the later rounds with bigger ranges, and try to nail the answer in as few guesses as possible.
Frequently Asked Questions
How do you play Number Bomb (Ultimate Password)?
The computer secretly picks a number within a set range. After you enter a guess, it tells you "too high" or "too low," and you narrow the range based on the hint and keep guessing. The goal is to find the correct answer before you run out of guesses. If you run out without guessing correctly, the bomb explodes and the game ends.
How is the guess limit calculated? Is it fair?
The limit is derived from the minimum number of guesses needed under the optimal "binary search" strategy (always guessing the exact middle of the current range), plus 2 extra guesses as a buffer. In other words, as long as you always guess the middle of the range, you're mathematically guaranteed to find the answer in time — this fairness has been verified through extensive random simulation testing.
Does the range get bigger as you play?
Yes. Starting at 1~50, clearing a round upgrades you in sequence to 1~100, 1~200, 1~500, and 1~1000, after which the range stays at 1~1000. Larger ranges also come with a larger guess limit, but the overall difficulty keeps climbing.
What are the rules for 2-player duel mode?
This is the classic Ultimate Password gameplay: the system secretly picks a number (neither player knows it), and the two players take turns guessing. Each guess narrows the range further. Whoever guesses the secret number loses — just pass the phone or device back and forth between guesses.
How is the score calculated?
Each round's score has two parts: a base score (determined by that round's range — bigger ranges give a higher base score) plus an efficiency bonus (the fewer guesses you use, the higher the bonus). To score high, push through to later rounds with bigger ranges, and try to nail the answer using as few guesses as possible.