Ask anybody to name some Mario puzzlers and you'll most likely hear Dr. Mario, maybe Wario's Woods, Yoshi or Yoshi's Cookie. They never name the best of the lot though — Mario's Super Picross, or its predecessor, 1995 Game Boy title Mario's Picross.
The original Mario's Picross had close to 200 puzzles. Basically, the object of the game is to chisel squares in a 15x15 grid to form a picture. Numbers on the sides of the grid hint which squares must be chiseled. For example, if there is a row of 15 squares and the number "10" next to it, that means that there are 10 squares next to each other in that row that have to be chipped away — but you wouldn't have any idea where to place your marks, as it could be the 10 to the far left, the far right or anything in between. However, if the numbers "10 4" were next to the that 15-squared row instead, you'd be absolutely certain - it means there's a row of 10 squares, then at least one empty square, then another row of 4 squares.
By taking in all the number data available, you can eventually smash away enough blocks to reveal a lovely hidden picture. Making mistakes causes you to lose time, which is a big no-no when you're up against time limits. If you run out of time, you must restart the puzzle. If you don't mind gambling with your time, though, you can spend five minutes on a hint, which fills a row and a column selected from a roulette wheel.
Game Boy's Mario's Picross also had a "Special" mode which didn't alert you to mistakes, thus leaving you in the dark as to whether you were solving the puzzle correctly or not. The time limit was not present here; instead, you had to beat puzzles as fast as possible to get a good time. There were only 20 or so puzzles, and a random one was picked each time.
Unfortunately, Mario's Picross was a commercial failure outside Japan, and so Nintendo did not release the sequels worldwide. Japan welcomed Picross 2 on Game Boy and Mario's Super Picross within the same year, and they were followed by eight downloadable SNES sequels over the next five years via the Japan-only Satellaview. Finally, in 2007, Nintendo released Picross DS worldwide, after 12 years of the games being exclusive to Japan.
Picross 2 for Game Boy introduced a few new elements. For starters, each puzzle was now 30 by 30 squares. They were all divided into four smaller, 15 by 15 segments; each puzzle was essentially four in one! The game also expanded "Special" mode into Wario mode, with many more puzzles. The rules for the mode remained the same, aside one small change: it gained a time limit. Picross 2 had about 200 puzzles — 100 Mario, 100 Wario.
Mario's Super Picross improved much upon Picross 2, and not all puzzles were huge any more. The game starts with small, five by five puzzles, and eventually ends with puzzles as big as 25 by 20 (An odd number, but it works). Again, there is a Mario mode with hints and a Wario mode with no hints. There are about 280 puzzles total, split evenly between Mario and Wario. Wario mode has no time limit in this iteration, so you can spend as long as you like on its puzzles.
The music in the games is also quite good. The original two games only had five songs during puzzle solving each, but you could select which one to play at any time — or switch the music off altogether. Super Picross features 10 songs — five for Mario puzzles, five for Wario puzzles. You can still select which to play, but you only get a selection of five per mode.
We must note that Mario's Super Picross is entirely in Japanese with the exception of a few words; it's presented in its original form. However, it is still very easy to understand, so you shouldn't run into trouble.
Mario's Super Picross is more of the same, but that's not bad at all, since, well, it's Picross! Whether you've played Picross before or not, Super Picross must be played — It's arguably the best in the series. Unlike the unforgiving first games, it's great whether you're a beginner or an expert, its difficulty starting off on the gentle side before ramping up as more puzzles are completed.