Binary Barrage Game

Alien invaders march down toward your flak turret, each carrying a binary number. Read it in decimal, so 1011 is 11, type it and fire to shoot the invader down before it lands. Start with 3 bits and work up to 8, until reading binary takes no thought at all.

How to play

1. Choose how many bits each invader carries: 3, 4, 5, 6, 7 or 8. With 3 bits the numbers run from 0 to 7, and with 8 bits up to 255.
2. Read the bits as one number. From the right, the bits are worth 1, 2, 4, 8, 16, 32, 64 and 128. Add up what the bits set to 1 are worth, so 1011 is 8 + 2 + 1, which is 11.
3. The lowest invader is the target, with its tag lit up. Tap another invader to aim at it instead, or press the left and right arrow keys.
4. Type the number. It goes into the slot under the bits. Then press FIRE.
5. A wrong number misfires. The invader drops closer, its slot empties, and the turret jams for 1.5 seconds before it can fire again.
6. An invader that reaches the ground takes one of your four shields. When the last shield falls, the game is over.

Wave 1 sends 6 invaders, and each wave after it sends 2 more. In wave 1 an invader takes 12 seconds to march down with 3 bits, and 1 second more for each bit after that, up to 17 seconds with 8. Each wave's march takes 8% less time than the last, down to half the time of the first. Two invaders are on the field at once in the first waves, and later waves bring up to four.

What you type for an invader stays on it when you aim at another, so you can come back to it. On a keyboard, type the digits, press Enter to fire, Backspace to delete one digit and Delete to clear them all. Escape or Space pauses.

Scoring

• An invader shot down on the first try scores 20 points for each bit, plus up to 20 more for each bit for how high it still is.
• An invader shot down after a misfire scores 10 for each bit.

For example, an invader of 6 bits shot down at the top of the sky scores close to 240, and one that misfired scores 60.

Your five best scores are saved in this browser for each number of bits, with the wave each game reached. In practice, no shield falls, each tag shows what every bit is worth, and a misfire shows the right number, so the game goes on until you end it from the pause screen. Practice games are not saved.

Reading binary for memory competitions

Binary is a standard event at memory competitions, with 30 digits to a row. A common method reads three bits at a time as one digit from 0 to 7, so a row is exactly ten digits. Those digits then become images with a number system such as the Major System, so 101 110 is 56, which might be a leash, and the images go into a memory palace.

Beginners lose most of their time on that first step, working out each group of bits. At 3 bits, every invader in Binary Barrage is one such group, so it drills that step until it is automatic. When you are ready to memorize real rows, practice with the binary practice tool, and read Binary Number Memorization Systems for more ways to encode binary, including grids of nine bits and the Ben System.

Try our other free memory games, such as Periodic Panic for the periodic table or Echo Invaders for working memory.