A varied blog about game design, development, and production from an experienced industry game dev turned indie, with a number of iOS titles under his belt. Also includes discussion of the business side.
Detailed, technical articles on the fundamentals of the plumbing of game development, with a focus on networking and physics. From The Network Protocol Company, who appear to be a consultancy for, you guessed it, game networking.
A blog about game design centred around the design of Magic the Gathering, by veteran designer Mark Rosewater. Although not strictly about video game design, the principles explored apply to all flavours of game design.