How to play Glowsum
Find every hidden number. No guessing is ever needed: every puzzle has exactly one answer that logic alone can reach.
The two rules
1. Each number once. On a 5×5 board every row and every column holds 1, 2, 3, 4 and 5 exactly once.
2. Embers show heat. An ember is a glowing cell. Its big number is its heat: the sum of the hidden cells around it. Its small number (top left) is the ember's own number. Other embers never count towards a heat.
Tap an ember to light up the cells it counts.
Embers and marks you will meet
Ember (dots): the 8 cells around it.
Cross ember (+): only the 4 cells it touches by an edge.
Diagonal ember (×): only its 4 corners.
Forge ember (×24, square): multiplies the 4 cells it touches by an edge.
Hollow dot: the number is odd. Filled dot: the number is even.
Cold cell (❄, blue): holds a number but gives no heat (counts as 0).
Hot cell (🔥, red rim): gives double heat.
Tools
Notes: pencil in the numbers a cell might be. Auto-notes fills every empty cell with what its row and column still allow.
Hints come in three steps: where to look, why (the logic in words), then the number itself. You get 1 free hint a day; more cost Cinders.
Check: the board checks itself when it is full; press Check again after fixing. A wrong check costs a try (5 tries, one back every 30 minutes) and marks what is wrong. Your first wrong check on each level is free.
Stars: 3 stars for solving on the first check with no hint, 2 stars without a hint, 1 star for solving.
Keyboard: arrows move, 1–7 fill, Shift+number for a note, N notes mode, A auto-notes, H hint, Backspace erase, Ctrl+Z undo.
Questions
Do I ever have to guess?
No. A solver checks every puzzle and only keeps the ones that logic can finish, step by step, with one answer.
Where do I start?
Look for an ember with only one or two hidden cells around it, or a row that is almost full. A heat of 3 over two cells can only be 1 + 2.
What happens when I run out of tries?
You can keep placing numbers and notes. A new try comes back every 30 minutes, or refill with Cinders, a rewarded ad or the shop. Finishing a chapter refills your tries.
What are Cinders?
The game's coins. You earn them from new stars, the Daily, the Weekly, chests and achievements, and spend them on hints.
What is the Daily?
One hard puzzle a day, the same for everyone, with a leaderboard timed by the server. The Weekly has five puzzles.
Does my progress sync?
Sign in with your Ember ID (Google, Apple or an email code) to keep progress across devices. It is also saved on this device.