One of the fascinating possibilities of the iPhone is to use the accelerometer to guide objects through mazes. This can be done with mazes in a literal sense, like in Labyrinth, or in a somewhat less maze-like setting, as in Super Monkey Ball. In these apps, the problems have to be solved through dexterity: a steady hand and smooth movements are necessary reach the goal.
In contrast, the principle of tilt mazes is to only use logic to reach the goal. The basic idea of such mazes is that the maze can be tilted, but the movements of all objects in the maze continue in the direction of the tilt until a wall (or hole) blocks the movement. As far as I know, Andrea Gilbert was the first to propose such puzzles in 1999.
There are three implementations available in the app store that use this principle (links redirect to iTunes):
These puzzles are clearly related to the “movement-until-blocked” puzzles that I discussed in this post and in this post, but the overall design of those puzzles result in a more abstract maze structure, compared to the very concrete visual maze structures present in the puzzles discussed in this post.
Ivory Tiles (shown to the left here, and at the top of this post) is a beautifully made tilt maze. The white tiles have to be tilted to the dark brown floor tiles by using the blocking of movement at the sides of the tray, or at the dark brown blocks inside. An interesting twist is the usage of a cut-out second level of the tray (as can be seen in the middle of the example at the top of this post). Blocks can fall down into this ‘pit’, and cannot be lifted up again. Depending on the goal, you will have to reset the puzzle if a block falls down. Blocks can also slide over blocks in the lower level, and even slide together when they start out on top of each other.
Overall, Ivory Tiles is gorgeously made, and the idea with the two layers is a real innovation. Unfortunately, the first 70 levels are all extremely simple. You will have to work your way through them to reach the interesting last 10 levels in “Heavens”. The level shown here to the left was particularly challenging. It looks simple, but it turns out to be really tricky, with a real ‘aha’ effect once you find the path to the solution. That’s the spirit of a good puzzle! Notwithstanding the many simple levels, this app is a most-have for puzzle fans—and let’s hope the developers add some more complex levels later on. Better still: let’s hope they offer puzzle packs to be designed by others, because I think the puzzle-principle that Ivory Tiles offers has much more puzzling power hidden in it than is currently shown in the available puzzles.
HupplePupple (shown here to the right) is also a straigtforward tilt maze, nicely shown in 3D. Not only do you have to reach the goal (the yellow ball at the lower left), you also have to pass through all the hearts. These intermediate goals could lead to more complex paths, but in the levels I tried it did not lead to interesting complications. There are also movable blocks implemented, which move maximally one tile when bounced into. This could be used to make complex Sokoban-style puzzles, but currently their function is not really used. The idea of this app is nice, but unfortunately the implementation is unbearable to watch for longer than a few minutes. Everything is bouncing and moving, making it impossible to enjoy. I don’t think puzzles really need a polished interface, but they should also not be distracting.
BloXoR (shown here to the left) is a good-looking combination of a purely logical tilt maze with some levels that involve dexterity. I particularly like this mix, although I miss the completely free choice of levels, so people who don’t like the dexterity puzzles can simply pass them over. There are various additions to a pure tilt maze, like one-way passages and bombs that can clear a blocked passage. Also the goal is different from the previous puzzles. In BloXor you have to bring together three blocks, marked O, X, and O, in the OXO order. This often makes it necessary to use walls to align the three blocks. The most challenging levels of BloXor are the ones that need dexterity. Like with Ivory Tiles, I think the bottom line of this approach to tilt mazes has not yet reached by the levels currently included. Still, this app has a really high quality, and is money well spent.
It is a pity that many puzzles in the app store are rather unsophisticated in their level-design. It is of course necessary to offer simpler levels for beginners and for people that are not that experienced in solving this kind of problems. However, for the more experiences puzzler these puzzles are somewhat simplistic. Aggravating the situation is the fact that levels cannot be freely chosen, so you will have to wade your way through stupid and tedious puzzles to unlock the few more interesting levels. Please, developers (and I repeat myself here): let the user freely choose levels in such puzzle games. Locked levels might make sense in arcade-style games, but not with purely logical puzzles!
To finish off this post, let me list some resources on tilt mazes on the web:
- A large collection of well designed tilt mazes is available at Andrea Gilbert’s Tilt Collection.
- Many complex designs on small grids are made by Ishihama Yoshiaki: 2 Ball Mazes, part 1, 2 Ball Mazes, part 2, 3 Ball Mazes, and 4 Ball Mazes.
- Finally, there is also HexaRoll by Oskar van Deventer, who (as always) though things through into yet different directions and designed some tilt mazes on a hexagonal grid.
To all developers out there: simply ask these designers for permission to use any of these designs. I am pretty sure that they will be delighted to cooperate with you to get these puzzles on the iPhone.
[Update 24 January 2009] MunkyFun, the developers of Ivory Tiles finally released a lite version [iTunes Link] to try out this game. They also released Shift and Shift Lite, which is exactly the same game, though with a different layout and with new levels. More tilt mazes are available in Puzzle FLIP. There are great puzzles in that app, though there is unfortunately no free level choice.
Puzzling iPhone 
4 January 2009 at 3:51
As a historical footnote … Scott Kim for one mentioned to me he independently invented “tip mazes” around 1996 and incorporated one or more into a Nintendo 64 game he designed. I would be interested to know of any earlier uses of the tilt-rule.