[Continuing our GDC coverage - also see official Gama microsite - here's the awesome Petri Purho talking about crayons, physics, and things.]

In a humorous speech on the Monday of the Independent Games Summit, Kloonigames' Petri Purho talked about what he learned in creating IGF 2008 Grand Prize Winner Crayon Physics Deluxe, stressing the importance of rapid prototyping in its genesis.

As he noted in the speech, "doing prototypes really worked out well for me," and it also gave him a hint towards which of his seven-day-created Kloonigames freeware games would break out, based on download counts.

He averaged 2,000-3,000 downloads of his previous prototypes, until the Crayon Physics prototype did around 25,000 free downloads in one month, and increased again to 250,000 when his YouTube demonstration of the game became incredibly popular.

Prototypes were great, Purho said, because you can "get the bad game ideas out of your system," and also pointed out that keeping to strict monthly prototypes helped him explore ideas that might not work, but he can also sometimes tell partway through that the game isn't up to snuff.

As to how the game was conceived, most other physics games like Armadillo Run are engineering-like, and have only one or two solutions -- on the other end of the scale are sandbox-like titles like Line Rider. Purho was looking to split the difference and get both sandbox-style and goal-centric elements into his game.

He explained the concept behind Crayon Physics Deluxe: "The game is not about finding the right solution to the puzzle, it's about finding a creative one." But, he asked, how do you detect when players are being creative?

In addition, Purho noted, a lot of people are lazy and will go for the easiest solution possible. In the end, for many of the core gamers who had interest in Crayon Physics Deluxe, the game was somewhat too easy -- something Petri didn't expect because his idea of the target market for the game was not that clear, he thought.

One of the biggest issues Crayon Physics had was the number of clones it created online, and Purho actually said at one point that an iPhone game called Touch Physics offered him money as a tribute, but he felt uneasy about accepting it. Overall, the clones made him initially angry, but his game sold well despite them.

The end result was an influential and playable title, and Purho said over 80,000 people signed up via email alone to find out when Crayon Physics Deluxe was going to be released, and his method of allowing pre-orders helped to get people to sign up before the game actually debuted.