Yeah, I really ran out of time because of travel plans. I had more robust plans for a slower, step by step guide - by tried to do things by text since I ran out of time. Here's my longer version if you want to try it again, and if it works I'll update the game.
- The "detection area" is the diagonally shaded area between the horizontal arrows and the vertical arrows. If it says zero, none of the boxes in the area have bombs. You can click each box once to mark with a red X. (This is optional to solving the puzzle - it's more of a guide to the player to keep track of where they've been and what they know.)
- To move the detection area - click and drag on the arrows. The arrows on the top and bottom can be moved left and right to change the columns in the detection area. The arrows on the left and right can be moved up and down to change which rows are in the detection area.
- If you know a box has a bomb click on it twice to mark it with a green check mark. If you are unsure you can leave it blank or mark it with the blue "?"
- Click the big checkmark in the bottom right to evaluate if you are right or wrong. If you've marked all the correct boxes with green check marks you'll move on. (For the first tutorial level with 5 horizontal boxes, it's the second and fourth box. You can learn this by only moving the vertical boxes one column at a time and watching the detection counter go 0,1,0,1,0 for the JAM version.)
[EDIT: I uploaded a new version with a slightly more intuitive tutorial. Let me know if it helps.