Unlock the door
The invalidation game

The crayon trail


One evening, after thinking it over for some time, Harold decided to go for a walk in the moonlight...He made a long straight path so he wouldn't get lost. And he set off on his walk, taking his big purple crayon with him. --Harold and the Purple Crayon

Crayon Physics Deluxe designer Petri Purho cites the classic children's book, Harold and the Purple Crayon, as an inspiration for his wonderful new game. It's a nice homage, and the connections between the two are easily seen. But as Purho freely admits, he hadn't read Harold while working on the game; "but I knew the plot and the magic crayon."[1]

The real inspirations for CPD suggest a fascinating design-influence circle that accounts for why, to me at least, CPD functions as a perfect companion to one of my favorite games of last year: World of Goo. Sure, both are physics-based games, but so was Spacewar! back in 1962. It's possible to find more precise and more interesting connections.

Purho credits Armadillo Run (2006) as his primary influence on the physics puzzle aspects of CPD's design.[2] In Armadillo Run the player builds structures in order to transport an armadillo to a specific location on the screen. The realistic physics simulation frees the player to identify multiple solutions for each level, from simple mechanisms to Rube Goldberg-esque contraptions.

Bridgebuilder Armadillo Run designer Peter Stock has cited Bridge Builder (2000) as a game that helped inspire the construction elements of his game. [3] Bridge Builder challenges the player to design bridges to allow a train to pass over chasms while sustaining as little damage as possible and staying within a fixed budget. Like Armadillo Run, the game encourages the player to explore a variety of creative engineering solutions.

Which brings us back to World of Goo and its opening chapter level entitled, appropriately, "Ode to Bridge Builder." Our tidy little design circle is complete, at least for now. The momentum behind physics-based puzzle games is strong and growing on all platforms, including devices like the iPhone. I have a feeling this circle will only get bigger.

WorldOfGooBuilding Of course, artistic roots rarely grow from single sources. World of Goo isn't merely the product of Bridge Builder and Armadillo Run. There's a bunch of Worms and Lemmings crawling around in there too. And Crayon Physics Deluxe, as Purho happily attests, also owes part of its existence to Braid. Which leads us back to not only Super Mario Bros., but also to literature (Calvino) and film (The Matrix)...and I'm just going to stop right here, or before long I'll be talking about Master Chief and the Iliad, and such things are better left to others. :-)

Tomorrow I'll return with more on why I think Crayon Physics Deluxe is such a successful game.