Codex

Your mission:
Break into the most secured fortress in the world, to steal the treasures it contains. All the treasures are kept in a single safe, protected by 100 levels of security.
Each level of security consists of a light puzzle: you must switch on all the lights to succeed. To switch on the lights, you must use a key (called pattern) that will toggle the state of a set of lights.
The fortress' security system recognizes 4 different patterns, and you are given the first one.
As you progress in the fortress, each level becomes more difficult, so you'll definitely need to unlock the 3 other patterns. Use each pattern wisely to switch on all the lights.
The system also knows how to estimate your skills, and will grant you new patterns if you unlock some achievements.
Good luck.