Which Namco game was Pac-Attack adapted from?

Pac-Attack was adapted from Namco’s Cosmo Gang the Puzzle. Namco reworked the 1992 falling-block puzzle game for overseas markets, replacing its original Cosmo Gang characters and presentation with Pac-Man-themed graphics and mechanics while retaining the underlying puzzle structure.

In Cosmo Gang the Puzzle, players drop formations of blocks and alien-like Jammers into a vertical playfield. Blocks disappear when complete rows are formed, while blue spheres defeat Jammers. For the Super Famicom version, Namco Hometek proposed turning the game into a Pac-Man title because the Cosmo Gang characters were not considered well known enough outside Japan.

The result, Pac-Attack, was released in 1993 and added familiar Pac-Man elements, including ghosts and a Pac-Man piece that could clear enemies. It was also released in some regions under the title Pac-Panic. The common mix-up is assuming Pac-Attack was derived from a better-known puzzle game such as Columns or Puzzle Bobble; its direct Namco predecessor was Cosmo Gang the Puzzle.