Flippy the Train vs One Line

Build a train track to solve digital circuitry puzzles! Flippy the Train rides the rails, flipping switches to model basic digital circuitry: NOT, AND, and OR logic gates. After building these basics, reuse them in larger tracks to create the more-complex XOR gate and half-adder. What is the fewest number of track segments required to build a half-adder? Includes a sandbox mode for creating arbitrary track for Flippy to ride.

One line. Every square. A calm, surprisingly deep path puzzle: trace the numbers in order — 1, 2, 3 — and fill the whole grid with a single stroke. A fresh daily puzzle turns spare minutes into the perfect little brain break. ■ How to play - Start your line at 1 - Pass the numbers in order: 1 → 2 → 3 … - Visit every open square exactly once (dark blocks are walls) - Finish on the last number. Drag back to erase, or touch any point on your line to redraw from there ■ Why you'll like it - Always fair: every board is checked by a solver, so there is exactly one solution — no guessing - Endless boards: puzzles are generated on your device and prepared in advance, so there's no waiting - Daily puzzle: the same board for everyone each day — build your streak - Four difficulties: gentle 6×6, 7×7, hard 8×8 and a fiendish 8×8 - Ranks: climb from Novice to Grandmaster; harder boards count for more - Progress: clears, streaks, best times and no-hint rate - Dark mode, in English and Japanese ■ Made for you if… - You want a quick, satisfying "solved!" on a commute or coffee break - You love logic puzzles but dislike ambiguous ones - You'd like a small daily habit that keeps your mind moving - You prefer a clean, quiet, grown-up design ■ Private by design - No account or sign-in - Your progress stays on your device and is never sent to a server - Puzzles are generated and played offline - The only network use is reading public App Store information to show other apps from the same developer - No third-party ads or tracking