Beginner's Guide
Asteroid Field is a pure logic puzzle — every asteroid can be located by deduction alone. Once you understand five rules, every puzzle becomes a satisfying chain of reasoning from the first click to the last safe sector.
The Rules
Reveal a sector to scan it
Tap or click any unrevealed sector. If it contains a hidden asteroid, the game ends. If it is clear, a number appears — or the cell is blank. A blank means zero asteroids in all eight surrounding sectors, and the game automatically reveals the entire connected safe area.
Numbers count all eight neighbors
A revealed number tells you exactly how many of the eight immediately surrounding sectors — up, down, left, right, and all four diagonals — contain a hidden asteroid. A 1 means one neighbor is lethal. A 5 means five of the eight surrounding sectors are dangerous.
Flag confirmed asteroids
Long-press (mobile) or right-click (web) to place a flag on any sector you are certain contains an asteroid. Flags cannot be accidentally revealed — a flagged sector must be unflagged before it can be tapped. Use flags to lock in your deductions and prevent costly mistakes.
Your first click is always safe
The asteroid layout is generated after your first tap, so the sector you click first — and all of its immediate neighbors — are guaranteed to be clear. You will always get at least one number or a blank cascade to start reasoning from.
Clear the field to win
The game is won when every sector that does not contain an asteroid has been revealed. You do not need to flag every asteroid — revealing all safe sectors is sufficient. The remaining unrevealed sectors are confirmed as asteroids at the end.
Tips for Your First Game
Start with a blank cascade
Click near the center of the grid on your first move. A blank (zero) sector anywhere in the field triggers an automatic cascade that opens up a wide safe area and gives you many numbered edges to work from. Corner and edge clicks tend to produce smaller opening cascades.
Work from constrained numbers first
A number surrounded mostly by already-revealed sectors has fewer unknown neighbors — meaning fewer possible asteroid positions. These constrained numbers often resolve immediately. Scan for cells with only one or two remaining unknowns before spending time on high-number cells with many unknowns.
Count remaining unknowns against the number
If a revealed number equals the count of its remaining unrevealed neighbors, every one of those neighbors is an asteroid — flag them all. If a number equals the count of flags already placed around it, every remaining unrevealed neighbor is safe — reveal them.
Use flags to track your deductions
Place a flag the moment you are certain a sector is an asteroid. Flags are not just visual aids — they let you count flagged neighbors against revealed numbers, which in turn reveals additional safe sectors. A well-placed flag can unlock a chain of free reveals.
Common Mistakes
Clicking without counting
Before revealing any sector, count how many of its numbered neighbors it satisfies. A sector that would exceed one of its neighbors’ counts is an asteroid. A sector that is the only remaining unknown of a fully-satisfied number is safe. Never click on instinct — always verify against at least one adjacent number.
Forgetting diagonal neighbors
Adjacency includes all eight directions. A number in the top-left corner of the grid still counts its bottom-right diagonal neighbor. Beginners frequently overlook diagonals and miscount, leading to incorrect flag placements or missed safe reveals.
Flagging without certainty
Flags should only go on sectors you have logically confirmed as asteroids. A flag placed by guesswork interferes with subsequent deductions — if the flag is wrong, every count that relied on it becomes corrupted. Only flag when a number forces the conclusion.
If You Enjoy Similar Games
If you enjoy Minesweeper, Asteroid Field will feel immediately familiar — the same adjacency-number logic, the same first-click safety guarantee, the same satisfaction of cascading reveals. The space theme gives the deduction a fresh coat of paint, but every technique you know from Minesweeper transfers directly. Players who have tried Minesweeper on Windows or any browser version will be solving Asteroid Field puzzles from their very first game.