Long before HTML 5 or iPhone apps, one of the most creative forms of online gaming was web-page riddles. Internet explorers looking for some mental rush would navigate to a page, find enough information to solve a riddle, then figure out how to input solutions. As a mode of gaming, it was minimally interactive and surprisingly engaging. There was always the feeling that one had stumbled upon a special thing, and solutions felt earned.

The early entries in the genre, published in the late 90s, were simple: Answers were found in either a hidden hyperlink on the page, or a word or phrase to be added to the URL in the address bar. But as technology began to advance in the early 2000s, the riddles got more complicated. In some of the more advanced games, players were required to access raw HTML code, or use photo software like GIMP to find clues hidden in images. These riddles were elaborate and engrossing in new ways. They attracted — in part, because the world was more connected than ever before — a vast audience.

A decade later, online gaming looks very different, but many of the best web page riddles are still around, and still compelling. Here are five of the most interesting.

Not Pron

The first level of NotPron

Billed as the “hardest riddle available on the internet, David Munnich’s Not Pron, boasts over 17,000,000 visitors since 2004, yet only 34 people have finished the mammoth 140 level puzzle. It starts innocuously enough: click a photo here, tweak a URL there. However, after a few levels, Not Pron requires you to not only use your wits, but to do some research. It’s the perfect combination of a logic puzzle and an online scavenger hunt.

Amnesya

The answer is staring you right in the face

Created in 2006, Amnesya is one of the more hardcore games in the genre. According to the website, none of the over 7 million players have been able to complete the game. The artwork and concepts are well done, and though it has a fairly high learning curve (you’ll need both photo and audio editing software), the tutorials do a great job in pointing players in the right direction.

E.B.O.N.Y.

Which looks like a pile of garbage...

E.B.O.N.Y advertises itself as “the weirdest riddle game on the internet” and that’s not hyperbole. It’s much more surreal than the other entries on the list, due in large part to the running narrative. Instead of simply solving brain teasers, you are working your way through a rather immense and intense story line. Often, the “logic” may not seem that logical, but once you get a sense of it, you’ll appreciate how the puzzles were constructed.

Odd Pawn

It get's a bit tougher from here ...

Odd Pawn is an immensely long game, but is perhaps more cheeky and a less intense than the other entries on our list. With an answer box on the page, it’s a bit easier to manage than the other games that utilize web browsers. And though the game is massive (over 300 levels), it’s broken down into selectable chapters for more bite-size doses.

The First Door

The dark is your friend

The First Door is the most straightforward riddle game on our list. No need to access source code or download any photo or audio editing software. Just follow instructions, use logic, and type the right answer into the address bar. That’s not to say it isn’t challenge, or that the puzzles aren’t just as satisfying when you finally figure them out, but if you’ve never played an online riddle game before, The First Door is a great place to start.

Photos via notpron.com, amnesya.com, http://ebony.extra.hu/, oddpawn.com, First Door, Amneysa.com