Tetris started a craze for puzzle games that continues even today. Klax was developed as an arcade game by Atari as a follow-up to Tetris in 1989. It was then ported to a wide variety of home systems starting in 1990 under the Tengen label. This particular ad is for the Sega Genesis version but other versions include NES, TurboGrafx-16, Sega Master System, Atari Lynx, PC/DOS, Commodore 64 and even the Atari 2600 among others and it has been released on various retro compilations a number of times since.
Klax is a relatively simple game in concept. Colored tiles roll toward you on a conveyor belt and you have to manipulate them into the appropriate location. It was originally written on an Amiga in AmigaBASIC in just a few weeks. Nevertheless, it was a relatively successful game winning a number of awards.
Klax seems a bit underrated to me today, at least if you like puzzle games. It is unique enough to not be just another Tetris clone and if you like puzzle games, it is well worth checking out. Unfortunately, it hasn't really been released on modern systems. The Sega Genesis and TurboGrafx-16 versions are great if you have those systems. Otherwise, it was released on the Arcade Party Pak for the PlayStation and later as part of Midway Arcade Treasures in 2003 for the PC, Xbox, GameCube and PS2. There are also portable versions with the Atari Lynx version being the best but it is also good on the Game Boy Color and Game Gear.