Random digit pair — type the mod-10 sum. Benchmark: < 1 second.
Complement Flash
Random digit — type its tens complement. Benchmark: < 1 second.
Running Sum
Digit stream — type the running mod-10 total. 20 digits.
Encode Flash
Random character — type its checkerboard code. Benchmark: < 2 seconds.
Decode Stream
Digit code — type the decoded character. Benchmark: < 3 seconds.
Five-Group Transcription
Digit stream — type it in five-groups (space separated).
Speed Encrypt
Short word + key — type the ciphertext.
Speed Decrypt
Ciphertext + key — type the plaintext word.
Cascade Detection
Corrupted ciphertext + key — type the position of the error.
Position Tracking
Pad consumption — type the next line number.
GAMES
Mod-10 Duel
Hot-seat two-player. Random digit pairs — first to type the correct sum scores. Best of 20.
RULES
Two input fields appear side by side (P1 blue, P2 gold). A random digit pair is shown. The first player to type the correct mod-10 sum scores a point. 20 rounds. The player with more points wins.
Complement Hunt
6x6 grid of digits. Click the complement of the highlighted digit. 60 seconds.
RULES
A 6x6 grid of random digits appears. One digit is highlighted. Click any cell containing its tens complement. Correct click = +1 point, new round. Wrong click = brief red flash. Timer counts down from 60 seconds.
Checkerboard Bingo
5x5 card of characters. Digit codes called — mark matching characters. Time to blackout.
RULES
A 5x5 grid of random characters from the checkerboard appears. A digit code is called. Click the character that matches the code. Timer counts up. Complete when all 25 cells are marked. Fewest misclicks and fastest time wins.
Three steps: (1) Encode a word via the checkerboard, (2) Add a key digit-by-digit mod-10, (3) Format the result into five-groups. Each step is timed. Complete all three for total time.
Error Injection
Decrypt a message with planted errors. Find and fix them.
RULES
A ciphertext is shown with 1-3 deliberately corrupted digits. Using the provided key, find and click the corrupted positions. Fewer misses and faster time = better score.
Position Audit
Track pad consumption across messages. Identify the correct next pad line.
RULES
Five messages of varying length are presented one at a time. Each message consumes a certain number of pad lines. After each message, type the next available pad line number. Track your accuracy and time.