TurtleFlip & Adiro: alienated peg jump

turtleflip.pngWith this post, I will finally finish off the sequential removal puzzles, as far as I have found them in the app store (see all posts in this category). In a sequential removal puzzle, objects have to be removed according to some rules. By taking the wrong order of actions, you might end up in a dead end, so sequential removal puzzles can be seen as an abstract kind of maze (see my earlier primer on maze puzzles explaining this in more depth).  

In real-life physical puzzles, sequential removal puzzles are not so widespread, because it is difficult to find interesting rules for removal that are transparently executable while manipulating objects on a board. Peg jump is possibly the only physical sequential removal puzzle. In contrast, for computer games the principle of sequential removal is very widespread, because even rather unwieldily rules of removal can be easily implemented for a computer to consistently perform. No cheating or accidental errors can occur. Because the goal of removing things, viz. clearing the board, is so intuitively simple, many computer games use this principle (just look at the dozens of Bejeweled-like games in the app store). The differentiation between such games lies in the details of the rules of removal. Enter the twisted rules of TurtleFlip!

TurtleFlip (there is also a Lite version, and a Christmas Lite version) uses a very special set of rules of removal. In TurtleFlip you have to remove all turtles. The basic principle of removal is of the match-and-vanish type (which is frequently used in recent computer games, see all my posts in this category). In TurtleFlip, two or more turtles are removed when they form an adjacent group according to the following rules:

  • all turtles have to be of the same color
  • all turtles have to stand on their feet

To make such groups, you have one empty space to which you can slide a turtle (only orthogonally, somewhat alike to a sliding block puzzle). During such a slide you can choose to have the turtle stay how it is, or flip it from its feet to its backs, or flip it from its back to its feet. (Are you still with me? You see, the rules of removal can become pretty twisted!)

There is one extra complications: once you remove a group of turtles (mostly two, but sometimes three or four at a time, more is impossible), then not only the turtles vanish, but also the parts of the board where these turtles were placed disappear. The consequence is that the board is shrinking all the time, and a typical dead end consists of a removal which results in a separation of the board in two parts.

Although this really sounds complicated, it feels less twisted once you try it on the iPhone. It really feels very much like a traditional peg jump puzzle, though with a somewhat different logic. The visual implementation of TurtleFlip is very pretty, and the interaction with the puzzle simple and clear (tap to move, double tap to flip, that’s all). Try one of the lite versions, and see whether it appeals to you. I rather liked it.


There is another puzzle in the app store that seems to be rather similar in dynamics: Adiro.(shown here to the left). However, there is not much detailed information available, and no lite version, so I did not yet try out this one. Did anybody try out this one? Please report on your experiences in the comments!

[Update 27 January 2009] A Lite version of Adiro just became available, and it is indeed very similar to TurtleFlip. The rules are less complex, and that makes Adiro more transparent (and, as far as I am concerned, more enjoyable). The only move possible is to swap two adjacent stars (no flipping, no moving into open spaces as in TurtleFlip). When adjacent stars are of the same color, they disappear. As there are no stars in those spaces, there is nothing to swap anymore, which has the same effect as the shrinking board in TurtleFlip. The problem is the same: find a strategy to remove all stars. Great casual puzzle!

As for the solution strategy: I don’t have a definite strategy yet, but the 5 x 5 puzzles with three colors in the Lite version are definitively doable with some caution. Keep removing starts from the side (don’t look at the screenshot above for an example). Watch out for uneven numbers of a particular color, because it might leave you with a single star of this color. Also, look for stars that are far away from their color-brethren (for example, the red star in the upper left in the screenshot): they have to be moved to the rest for a solution to be possible. Further, don’t give up to quickly when a situation seems to be a dead end.


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