right-clicking in the laser firing range above/below that column, or
to the left/right of that row.
+The cursor keys may also be used to move around the grid. Pressing the
+Enter key will add a new ball-location guess, and pressing Space will
+lock a cell or a row/column.
+
When an appropriate number of balls have been guessed a button will
-appear at the top-left corner of the grid; clicking that will mark
-your guesses.
+appear at the top-left corner of the grid; clicking that (with mouse or
+cursor) will mark your guesses.
If you click the \q{mark} button and your guesses are not correct,
the game will show you as little information as possible to
in future. Left-clicking again on a highlighted island will unmark
it and restore your ability to modify it.
+You can also use the cursor keys to move around the grid: if possible
+the cursor will always move orthogonally, otherwise it will move
+towards the nearest island to the indicated direction. Pressing the
+return key followed by a cursor key will lay an island in that direction
+(if available); pressing the space bar followed by a cursor key will
+lay a \q{non-bridge} marker.
+
+You can mark an island as finished by pressing the return key twice.
+
Violations of the puzzle rules will be marked in red:
\b An island with too many bridges will be highlighted in red.