With 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!