Cosmos Lines Walkthrough & Level Guide

Overview

Cosmos Lines is a grid-fill logic puzzle, not a reflex game. Each numbered point sprouts a single line that must be drawn to exactly the length of its number, and all the lines together have to tile the board with no overlaps and no gaps. You solve a level by working out how the fixed-length lines interlock. This guide gives you the repeatable method plus the traps that make the later packs hard.

How Cosmos Lines levels work

Sequential, handcrafted grid-fill puzzles grouped into difficulty packs, with grids growing larger and more constrained as you progress. (~100 levels).

Stage-by-stage strategy

The method that solves any level

Read the board before you draw. The longest lines (the biggest numbers) have the fewest possible routes, so place them first — lock in the 5s and 6s, then fit the shorter lines into what is left. Treat every line you have already drawn as a solid wall the other lines cannot cross. Because the numbers add up to the total number of cells, a finished board has zero empty squares; a leftover gap means a line is misrouted, not that the level is impossible.

Start from the edges and corners

A corner cell can be reached from only one or two directions, so it usually forces which line has to cover it. Fill the perimeter first to remove ambiguity, then work inward where more routing choices open up.

When you get stuck

Find an isolated pocket of empty cells and count them — if no remaining line of the right length can reach it, back up and reroute the nearest long line. Save the in-game hint for genuinely stuck boards: reveal one correct line, then reason out the rest yourself.

Tips to beat Cosmos Lines faster

• Place the highest-numbered lines first — long lines have the fewest possible routes, so locking them in early narrows every other choice.
• Work from corners and edges inward; a corner cell can only be entered from one or two directions, which often forces which line must cover it.
• Treat every line you have already drawn as a solid wall — remaining lines cannot cross it, so each placed line reshapes the options for all the others.
• Watch for isolated blank cells: if a pocket of empty squares can't be reached by any line of the right leftover length, back up and reroute.
• As a sanity check, the lengths of all the numbered lines should add up to the number of cells to fill — so if you can’t cover the whole grid, a line is usually misrouted rather than the puzzle being unsolvable.
• Save the built-in hint for genuinely stuck boards — reveal one correct line, then reason out the rest yourself.