Blindfold Sudoku Mini – An Intro to Sudoku

After Judy Dixon and I collaborated on Sudoku, she recommended I create simpler versions for children, or for adults who have never played Sudoku before.  Blindfold Sudoku is based on a 9 by 9 grid; it amazes me that visually impaired people can solve these types of puzzles without using the screen.  instead they keep all of the relevant rows and columns and squares in their head, as they move to the solution.

sudokuk 4x4 grid

To get started playing Sudoku, I don’t recommend tackling the 9 by 9 grid; Sudoku Mini uses a 4 by 4 grid, so it’s much, much easier.

The first version was just like the 9 by 9 game: several of the cells on the grid are already filled out, and you have to complete the rest of the grid so that a number appears only once in each row, column and 2 by 2 square.  The 2 by 2 squares are in the upper left, upper right, lower left and lower right.

The game is navigated like solitaire: you move within the 4 by 4 grid by flicking left, right, up or down, and the game tells you the number in the grid, and whether or not that number is part of the original puzzle, or was your guess.  To place your guess into a cell, you tap the screen twice, and it pops up a keypad for you to enter the number for the cell you are in.  If you aren’t sure, you can put several guesses into that cell, and then later, when you know for sure, remove the incorrect choice.  If you guess violates the puzzle rules, the app makes a honking sound, and rejects your guess.

Since Judy and I thought children would like the game too, we came up with including animal sounds, and animal names.  For example, one variant of the 4 by 4 Sudoku game is played with a dog that barks, a cow that moos, and frog that ribbits, and a horse that neighs.  Another variant says dog, cow, frog or horse for each cell.

Surprisingly, gamers of all ages like the fun sounds in Sudoku Mini.  We are planning on doing a 6 by 6 Sudoku, but we’re waiting for more people to request it.

Blindfold Bowling: Reliving the dream


There’s not much I can add to this email that I received earlier this week.

picture of mailbox

Hello Marty,

Now that I have mastered most of your bowling game, I need to tell you a story I think you will enjoy.  Your game is so life-like, and brings us the reallity of a live bowling alley.

I am totally blind, and I started bowling in 1966. I carried an average score of 136.  My high games were 148, and a 197. Other than that, I had the occasional game of 160.  I bowled until 1985, when I was in a terrible auto crash. It left me with a shattered left leg from the knee down.  I would never bowl again. I really missed the game.

Since I have your game, I can now relive my dream of bowling.  It was my favorite hobby.  Many thanks to you, for bringing us a lifetime product.  This game just works.  It is just wonderful to use my fingers to aim at the pins and get a strike, and then throw the same kind of throw, and get fewer pins.  I am so happy.

Thank you Marty, and keep up the good work



Blindfold Bowling: How to avoid throwing your iPhone

This is the next in series on how Blindfold Bowling was built.

Once I implemented the physics engine  into Blindfold Bowling, I needed a way to let a player both aim and throw a bowling ball.

person bowling

With visual bowling apps – where you see the action on the screen – you position yourself by moving your finger left and right  a picture of the bowling alley on your phone, and then you swipe in the direction you want the ball to move.

In Blindfold Bowling –  an audio game – you position yourself by moving your finger left and right.  The game tells you where are: when your finger is on the left edge of the phone, a woman says five.  As you move your finger towards the center, the woman counts down to 1, then says “center’, then a man starts counting up from 1 to 5, where 5 is the right edge of the phone.

I asked the gamers how they wanted to choose the angle to throw the ball.  I got back so many different alternatives, the game comes with 3 methods.  The simplest is a straight throw.  After you position yourself, you swipe up.  The ball travels straight towards the pins.  It’s very easy, and it’s a great way for someone to learn how to play Blindfold Bowling.

If you want to pick an angle, you can use “One Finger Aim and Throw”.  First, position yourself on the bowling alley as described above, pause briefly, then, to aim, flick in the direction that you want the ball to go.

To be even more accurate in your bowling, use the “Two Finger Aim and Throw”.  Position yourself using your thumb (not your forefinger), and then touch your fore-finger on the screen, and rotating your finger left and right (while you keep your thumb in the same spot) until you have ball aimed exactly where you want.  Finally, pause briefly, then flick your fore-finger.

While everyone seemed to like these three methods, I did get a lot of gamers requesting another method.  Like the Wii device for playing games on a TV, they wanted to swing their arm as if they were bowling with the phone, instead of a bowling ball.  My fear was that people would be tossing their phones across the room.  I could just imagine the number of emails I would get telling me how much they loved the game, but now they needed a new iPhone.  Maybe I should sell a wrist strap to go with the phone, if I ever add that feature.

Blindfold Bowling versus Blindfold Skeeball

After I finished the new versions of Blindfold Pong and Blindfold Hopper, I asked my game testers what game they wanted next.  Many of them asked for a bowling game.  There are many visually impaired bowlers, and the American Blind Bowling Association helps set up leagues in each town across the country and elsewhere in the world, and holds annual competitions.

ball hitting pins

Bowling is a fairly easy game, but creating an version for an iPhone requires something none of my games had yet – the ability to simulate real world events, such as a ball hitting a bowling pin, and then that pin hitting another pin, as each pin falls over.

Most games use a physics engine to solve this problem.  A physics engine is a computer program that emulates real world events, such as one object hitting another, or the effects of gravity and friction on a bouncing ball.

I didn’t want to dive into incorporating a physics engine into the games, so I thought I would tackle skee ball first.  That’s a much simpler game, and from a quick study of the game, it could be done without a physics engine. You would flick the screen, and that would throw the ball into one of 5 holes, where the hardest hole to hit would earn 50 points, the easiest hole 10 points, and a bad throw wouldn’t earn any points.

When I announced the game, the testers had mixed feelings.  Some liked the game from their visits to amusements parks, and liked being able to trade in the paper tickets for cheap, fun rewards.  There are even some iPhone games that let you trade virtual paper tickets for virtual toys and gifts.  But most of the testers said they preferred a bowling game.

It took a few weeks, but I found a two dimensional physics engine called BOX 2D, that is easy to integrate into iPhone apps.  Most arcade games, like Space Invaders, Asteroids or Breakout, and many sports games, like Bowling or Pool, can be done with a two dimensional physics engine.

My next blog will discuss how a player can aim and throw the ball.

6 Hours playing Blindfold Breakout

I just received the following tweet: “I have not found a game that kept me entertained for 6 hours straight before, until I found Blindfold Breakout”.  I guess he likes the game.


We built Breakout at the suggestion of several blind gamers that liked Blindfold Pong, but wanted something more challenging. If you read my prior posts about using a physics engine, once we got over the learning curve of using the engine, there were lots of games that we could easily build.

I was about to re-create Pong with the physics engine, but decided that it’s not really worth the effort.  Pong, by itself, is pretty good, but there’s not much reason to improve it since the game is so simple.  Instead, I started looking at all of the variants of Pong, and decided Breakout would be a fun but challenging game.

Breakout is Pong with bricks that you hit with the ball that bounces back and forth.  As long as you can keep the ball in play by moving your paddle – controlled by moving the phone – left and right to you’ll smash more and more brick.  After you’ve smashed all the bricks, you move onto the next harder level, usually with more bricks.  Many of the blind gamers who test my games made suggestions on varieties of the game, prizes to win, and how to make the levels harder. I implemented all of their ideas, and released the game about a week ago.

The really interesting thing about Pong is that it is the basis for a lot of the early video games.  Breakout is Pong with bricks.  Space Invaders is Breakout with moving bricks.  Air Hockey is Pong with goals and a mallet.  Ping-pong and Tennis are three-dimensional version of Pong with movable paddles.   Bit.Trip Beat is Pong with moving musical blocks.  I also found a Poop-pong game, that involves poop, a toilet and a gorilla’s head.  And Nogginknockers is a bloody sports game where you knock a severed human head back and forth between two monsters that control a paddle.  I don’t think we’ll create the latter two games.

We have some more ideas for other games that are variants of Pong, but I will leave those for another day.