InfiniteUnity3d links to a collection of articles for casual game developers, and indie's thinking of taking the plunge.

The highlight is an article discussing Casual Games as a business, over at the main Unity3d site.

Y'know, some of the advice applies to writing tutorials too...

Think About Your Target Audience

Think about your game and its intended audience when choosing a distribution path. Free browser-based web games appeal to males in their teens and twenties who tend to prefer action, adventure or driving style games whereas downloaded executables appeal to an older and increasingly female audience that tends to prefer story-based or puzzle type games.

Always consider your target audience from a few different angles. What's the most likely age? Sex? What will they find funny? What will they find annoying? Don't think only about what technical stuff they know -- get a decent picture of your reader.

Reward Your Player

Keep players interested and engaged with the game experience. For example, in an action game you might offer a new weapon, power-up or enemy every 30 seconds or so for the first few minutes, then every few minutes for the next five to ten minutes, and so on. Or in a story-based game offer new items or character modifications on similar time scales to keep the player invested in the story and the game.

Your reader needs to like your book from the start Don't put lots of boring stuff at the front with the promise of later reward. Make it fun from the beginning.

What books should Packt be publishing for casual game developers? And other game developers?

Here's the article list: http://infiniteunity3d.com/casual-game-developer-advice-from-the-unity3d-website/