Over on ihobo today, some musings about Drop7 and the notion of volatilty in puzzle games. Here's an extract:
The essential play of Drop7 draws from the well established tile-stacking genre that flowers fromTetris. Whereas Pajitov’s classic relies on the simplicity of it's mechanics for its appeal (anyone can work out how to stack tetronimos), later tile-stackers such as Dr. Mario, Super Puzzle Fighter, Baku Baku Animal and Puyo Pop focus on combos to drive interest. The player learns to stack tiles in such a way that, when correctly prepared and then triggered, a giant chain reaction occurs. This reaction is the core of Drop7’s appeal as well, but unlike earlier stacking games Drop7 has a secret weapon in its rules. Failure in tile stacking games occurs when the board becomes stable, which results from a configuration where the reactive combinations of tiles cannot be made to come into contact e.g. in Super Puzzle Fighter, tiles of the same colour don't touch. Conversely, it is possible to stack tiles chaotically in such a way that a small landslide will trigger large (accidental) chain reactions. This quality, volatility plays almost no role in Tetris but has been core to all other tile-stackers since.
You can read the complete Drop7 and Volatility in Puzzle Games over at ihobo.com.