Cipher is an online riddle. It currently has 65 + 2 levels.

The simple goal in this game is to progress through a series of HTML pages. The challenging part is how this is achieved. Every page will yield a unique puzzle. You must solve this puzzle in order to progress to the next page or "level". These puzzles will range from dead easy to frustratingly hard, and they will increase in difficulty the higher level that you reach. A broad range of skills will be utilized in solving these puzzles, including technology, math, music, science, language, Internet smarts, and more. Some levels may require you to use an internet search engine (such as Google), while others will simply require you to use common sense.

So what are you waiting for? If you have some decent patience and a sharp mind, give it a go!