Source: Wikipedia, "Daedalian Opus", available under the CC-BY-SA License.
Daedalian Opus (冒険!パズルロード Bōken! Pazuru Rōdo, Adventure! Puzzle Road) was a puzzle game for the Game Boy released in June of 1990. It was one of the few games produced by the little-known software company Vic Tokai. Cover illustration by Lawrence Fletcher. The name of the game was inspired by Daedalus, the mythical character of Greek legend who created the labyrinth.
The game is essentially a series of 36 jigsaw puzzles with Tetris-like pieces known as pentominos that must be assembled into a specific shape. The puzzles start off with rectangular shapes and simple solutions, but the puzzles quickly grow more complex, with odder shapes like a rocket ship, a gun, and even enlarged versions of some of the pentominoes themselves. Each level is timed, and once the timer is started it cannot be stopped until the level is finished. One starts off the game with only three pentomino pieces, and at the completion of each early level, a new piece is awarded to the player. At the final level, the player is given the 2x2 square O tetromino and must complete an 8x8 square puzzle.
After completing each level, the player was given a password to access that level at a later time. Interestingly, each password was a common English four-letter word, so that by guessing common four-letter words, players could potentially access levels they had not actually reached by playing the game.
From the manual:
In the World of Daedalus there are puzzles houses on each of the 42 islands of this very puzzling land. On the first island there are no bridges and no ships. When you enter the puzzle house on this island you will find 3 Daedalian blocks. Your task is to fill up the frame in front of you with the blocks. There can be no space remaining! When this has been done, a bridge will appear, and you can go on to the next island.
However, you are in an apprentice stage until you get up to a point where you are using 12 blocks. While in this stage, you will find three blocks at the first island. When the sprite appears over the bridge, you will get another block and go on to next island by passing through the puzzle house. Only when you have gotten by your apprentice stage with 12 blocks, does the real game begin!
You will encounter many different types of frames. Some will be very challenging, but don't give up! When you have mastered all the puzzles on all islands up to 41, you will be confronted by island 42, where your final task awaits you. Here you will be presented with 13 blocks. Good luck!