An Ad-Free Sudoku Game

With AMOLED power-saving screens in mind, this is a lite-weight, fully blacked-out Sudoku game which doesn't consume your battery, device memory or require any permissions! It only weighs in at around 500KB compressed, the size of one selfie taken on most Android phones!

Features:
• 400KB on Android 4.x; 630KB on Android 5.x; expands to ~1MB total once installed
• Ad-free, tracking/statistic free, and distraction free (no 'rate us now!' or 'download this!' barriers)
• Zero device permissions on install
• Blacked-out monochrome background reduces strain on eyes at night and saves battery by completely turning off about 80% of display pixels on all Galaxy devices + newer flagship phones
• Easy, medium, and hard levels
• Entries are answer-checked immediately but only 5 errors allowed before a game forfeit; allows a few guesses here and there on the difficult Sudoku puzzles
• Does not hide notification bar

Non-features:
• No penciling or note-taking capability built-in.

This indie Sudoku game should work on all devices of any screen size. Layout is dynamic and supports landscape mode!

Actually tested devices:
• Galaxy S4, S5, Note 2, Note 4, S4 Mini
• Galaxy Reverb
• LG G3
• HTC One M7
• Moto G
• Dell Venue 8 Tablet (Android x86 / Intel Processor)

Bugs:
• Bottom border is 1 pixel too thin on some screens <4 inches; no plans to add special code to patch that issue
• Difficulty level resets after every Sudoku completion

Oh, and don't mind my #sudo Linux pun in gameplay.