ZNYK

ZNYK is, according to its documentation, yet another Tetris lookalike, but could just as well be based on Puyo Puyo, Pick 'n Pile or Columns.

From above, pairs of coloured balls come falling. The pairs can be swapped and rotated so as to match those balls already on the bottom of the screen. By making horizontal or vertical groups of four balls of the same colour, those groups are eliminated. The goal of each screen is to eliminate those balls present at the beginning of the stage, indicated by a white outline. The game then progresses to the next screen.

ZNYK is written in a mix of C and assembler, supports joystick or keyboard control and has a colourful, slick presentation with music, but is still multitasking-friendly. The source is (was) available for a small fee.