Ghost Grid: Signal Hunt

How to play Ghost Grid

1. Choose a mode: Battle the Computer, Create Online Game (you get a 6-character code to send to a friend) or Join with code.
2. Deploy your four clusters on the 9×9 field. Click a cell to place the cluster shown as “placing…”; Rotate switches between horizontal and vertical. Randomize places all four for you and Clear starts over.
3. Press Start Battle. In an online game the button reads Ready instead — the battle begins once both players are ready, after a five-second countdown, and a coin flip decides who fires first.
4. On your turn, click a cell on the Enemy Field to fire at it. A ✦ marks a hit and a · marks a miss.
5. Turns alternate strictly — one shot each, whether it hits or misses.
6. A cluster is sunk when every one of its cells has been hit. Sink all four enemy clusters before yours are gone and you win.

The four clusters

That is 12 occupied cells out of 81. Clusters always lie in a straight line, across or down. They may not overlap, but they are allowed to touch — which matters for strategy.

Field Tools

Against the computer you get two scanners. Click the tool, then click a cell on the enemy field. Using one does not end your turn — you still fire afterwards.

• Pulse Scan (2 uses) highlights the 3×3 block around the cell you click and tells you how many enemy segments are hidden inside it. Segments you have already hit are not counted.
• Echo Needle (3 uses) checks a whole lane through the cell you click — either its row or its column, chosen at random — and reports “activity detected” or “quiet lane”.
• Both tools are switched off in online games, so a match between two people is decided by shots alone.

Controls

Ghost Grid is played entirely with clicks or taps. There are no keyboard controls apart from pressing Enter to submit a join code, and the game has no sound. Every shot, hit and sinking is written to the Transmission Log, newest first, so you can always check what just happened.

Playing a friend online

• One player chooses Create Online Game and sends the code to the other, who enters it under Join with code. Codes avoid look-alike characters — there is no 0, O, 1, I or L — so they are easy to read out.
• Only shots and their results are exchanged. Each browser answers shots against its own board, so your layout never leaves your device and the relay in the middle could not reveal it even if it wanted to.
• If your opponent goes quiet for 45 seconds on their turn, a banner warns you they may have disconnected. If they close the tab, the game tells you they left.
• Games are temporary. The relay forgets a game an hour after the last activity in it.

Tips & strategy

• Search in a checkerboard. The smallest cluster covers two adjacent cells, and two adjacent cells are always one “black” and one “white”. Fire only at one colour and every cluster is guaranteed to be hit at least once — 40 or 41 cells to search instead of 81.
• After a hit, work the line. Try the four neighbours. A second hit tells you whether the cluster runs across or down — keep going in that direction, then back the other way, until it sinks.
• Don't assume empty water around a wreck. Clusters can touch, so the cells next to one you just sank may hold another.
• Scan where you know least. A Pulse Scan that returns 0 clears nine cells at once; one that returns 3 or more is worth several shots. Near the edge the scan covers fewer cells, so aim it at the interior.
• Know how the computer hunts. It fires at random on a checkerboard until it hits, then tries the neighbours of that hit. When it sinks a cluster it drops every lead it was following and goes back to searching — so clusters placed side by side can cost it a hit it never follows up.

How it's built

The whole game is about 400 lines of plain JavaScript driving ordinary HTML buttons — no canvas, no framework. Against the computer it never touches the network. Online games pass through a small relay: a serverless function that keeps a short-lived list of shot and result messages for the two browsers to read. Player IDs are random values created in your browser for that one game, and nothing is tied to an account or stored once the game expires.

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