Drop7

Drop7 is a numbers-based puzzle game where the player drops colored balls, some containing numbers, onto a 7x7 grid. If a ball's number matches the amount of balls in its respective row or column, the ball disappears. The goal is to keep the board from overflowing at the top; after each round additional rows of random balls are dropped onto the grid. The player ideally would set up the balls such that one ball disappearing would place other balls into position to disappear as well, creating a chain reaction.

The game has three modes: Normal, Hardcore, or Sequence. In the Sequence Mode, all players are given the same exact order of numbers each time, with the intent of developing a strategy.

Drop7 started out life as a Flash game called Chain Factor, released as part of an ARG (alternate reality game) for the CBS television program Numb3rs. An episode called "Primacy" (episode 407) revolved around the characters investigating the death of someone involved in an ARG. The episode featured clues that led viewers to the Chain Factor website, which features "error messages" and other such ephemera that unveil the story of a megalomaniacal game developer.

The campaign was considered successful, with the game receiving attention on a number of gaming sites. The game eventually received a face lift and name change, first appearing as a stealth release in the iPhone App store as snap7, then later making an official debut under its current name.