the following is copied from simon tatham's manual from the original implementation. ive struck out things that u can't do in this version
You have a square grid. On each square of the grid you can build a tower, with its height ranging from 1 to the size of the grid. Around the edge of the grid are some numeric clues.
Your task is to build a tower on every square, in such a way that:
In harder or larger puzzles, some towers will be specified for you as well as the clues round the edge, and some edge clues may be missing.
This puzzle appears on the web under various names, particularly ‘Skyscrapers’, but I don't know who first invented it.
Towers shares much of its control system with Solo, Unequal and Keen.
To play Towers, simply click the mouse in any empty square and then type a digit on the keyboard one of the number buttons to fill that square with a tower of the given height. If you make a mistake, click the mouse in the incorrect square and press Space to clear it again (or use the Undo feature). click the clear button
If you right-click in a square that is already selected and then type a number, that number will be entered in the square as a ‘pencil mark’. You can have pencil marks for multiple numbers in the same square. A square containing a tower cannot also contain pencil marks.
The game pays no attention to pencil marks, so exactly what you use them for is up to you: you can use them as reminders that a particular square needs to be re-examined once you know more about a particular number, or you can use them as lists of the possible numbers in a given square, or anything else you feel like.
To erase a single pencil mark, right-click in the square and type the same number again.
All pencil marks in a square are erased when you left-click and type fill in a number, or when you left-click and press space. Right-clicking and pressing space will also erase pencil marks.
As for Solo, the cursor keys can be used in conjunction with the digit keys to set numbers or pencil marks. Use the cursor keys to move a highlight around the grid, and type a digit to enter it in the highlighted square. Pressing return toggles the highlight into a mode in which you can enter or remove pencil marks.