GDC Vault

Game Developers Conference records, must see for any game designer. Big part of the content is paid, though. But even in the free part, you will find a lot of useful knowledge.

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Gamasutra

The biggest game industry online professional community. News, articles, blogs, forums, jobs, and many more.

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Game Designers Vault

Great place for game design beginners, with a lot of useful links and tutorials.

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Academia

If you’re looking for some academic knowledge about game design, this is the place. Just search “Game Design”.

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DiGRA

Digital Games Research Association – another good source of the academic knowledge about games and game design.

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GamesIndustry.biz

One of the best sources of information about the business side of the game industry.

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Newzoo

One of the best sources of information about game market trends and research data. Detailed reports are paid.

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Flurry Blog

Great source of the mobile game market research and data.

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Coursera

Free courses from the world’s top universities (game design courses included). If you’re looking for the source of fundamental knowledge in different areas, this is the place.

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TED

The best-known place, if you’re looking for new ideas, knowledge or just want some inspiration.

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