Welcome to X-Num! This game is similar to the "Challenger" puzzle that appears in some newspapers (the classified section of the San Francisco Chronicle, for example). The object is to enter a digit into each of the blank boxes, to make the rows and columns add up to the sums in the bold boxes. Also, the two diagonals must add up to the bold boxes at upper and lower right. Any digit from 1 through 9 may be used (and a digit may be used more than once). No boxes may be left blank in the solution. To create a new game, tap on the "New" button. Then, tap "Play" to start the game. ENTERING DIGITS Enter digits by drawing them, Graffiti-style, directly into the boxes. Remember that a '4' is drawn like an 'L'. Go ahead and write big - if a digit extends outside a box, that's ok, as long as it starts in the box. The value '0' may be used to blank out a box. Tip: if you stroke to the right in a box (like a Graffiti space), the digit will increment, and if you stroke to the left (backspace), the number will decrement. ADVANCED COMMANDS PREFerenceS may be set under the Options menu. New Game Generation: Manual or Automatic In Manual mode, the "New" button will clear the whole board, so you can enter a new game, such as one from the newspaper. In Automatic mode, when "New" is tapped, a game is generated automatically. If you don't like the present game, you can repeatedly tap "New" until you find one you like. Games generated this way will always have a solution. Any of the boxes, including the totals, can be edited before "Play" is tapped, but be warned that an impossible game could be created by doing so. Compute Aids: None, Totals, or Deltas As an aid to solving the puzzle, X-num can compute the sums of the rows, columns, and diagonals, and display the results next to the bold boxes, if desired. The None setting is best for exercising your addition skills. No aids are displayed. This is also the only way to have a meaningful victory over the challenge time in the Newspaper. With the Totals setting, the present sums of each row, column and diagonal are displayed next to the bold boxes - still a small workout for your brain. With the Deltas setting, the difference between the present total and the goal total is displayed. I find this setting to be the most useful. Fanfare: Off or On If the trumpet sound might embarrass or annoy you, it can be turned off here. This is primarily for Palm 1.0 users. Others should use the Game Sound volume in System Prefs. CHOOSE GAME Every automatically generated game has a number shown in the middle of the title bar. You can choose a specific game number with this menu pick. Enter a number from 1 to 65535. If you enter a larger number, it will be taken "mod 65536". If you enter 0, a random game will be generated. SOLVE This menu pick finds a solution to the present game, if possible. MANUAL GAME GEN AUTO GAME GEN These set manual or automatic game generation, as described under Preferences. Separate menu picks are provided as a convenience for this common operation. KNOWN QUIRKS, TO-DO LIST Technically, a game should have exactly one hint in each row, column, and diagonal, and should have all bold boxes filled in with totals. X-num does not check for this. It is therefore possible to enter a trivial game, or an impossible one. Recognition of the numbers could be better. I hope to add some trainability into the recognition in a later revision. Right now, the number recognition is based on statistics gathered from my personal handwriting. Most automatically generated games are quite difficult. Perhaps easier levels could be added in the future. The solver is brute-force (just keeps trying numbers), written for code size, not efficiency. The solver will probably fail if the hints and totals are not arranged in a strictly legal format. Finally, there are usually many solutions, but the solver only finds one. If you are interested in writing a better solver, please e-mail me for the source for the main program. However, the solver source will be omitted. This is not vanity; my solver is trivial. I am just following the lead of others who say that the solver is often an assignment for beginning CS classes. Look for a discussion of algorithms on the internet in the work of Brian MacBride (Challenger page) or Michael Glickman (XnX game for cell phones). X-num was compiled with the free prc-tools environment. Feedback is WELCOME - my web page is http://www.angelfire.com/ca2/roderick . If you find a bug, please note the game number if possible. My daughter, Kendra, designed the congratulatory screen.