Lots of great content for those in the publishing field (audio):

https://breakingintoboardgames.libsyn.com/breaking-into-board-games-episode-120-connor-alexander

“Use whatever tools you can to get to a first playable ASAP - scrap paper, rules in Notepad, scribbled diagrams etc. then play it out yourself or with someone ASAP even if (especially if) you realize it’s crap within 5 minutes and have to redo everything.”

— Aaron Lim

Lots of free 2D and 3D icons and elements for games:

https://kenney.nl/assets

Wargame designer Hermann Luttmann offers advice for new designers:

https://www.diagonalmove.com/so-you-want-to-design-a-board-game/

Erica Hayes-Bouyouris on designing for the hobby market vs. mass market, co-designing, working with an intellectual property, having an online presence, and more. (video)

Hermann Luttmann, designer of Dawn of the Zeds and At Any Cost, on designing wargames and historical-simulation games, working on solo games, small-scale vs. large-scale games, and more:

https://www.diagonalmove.com/interview-hermann-luttmann-designer-of-dawn-of-the-zeds-at-any-cost/

“If it stops being fun and feels like a chore, take a break. Come back to it when you’re feeling it again. When you play a game, you can feel how much fun the designer had making it, so ensure that you maintain your own passion for what you love throughout the process, and most of all enjoy yourself, so you know that your players will, too.”

— Tristan Hall

PNP Arcade has a “prototype zone” for print-and-plays with feedback forms:

https://www.pnparcade.com/collections/prototype-zone

Lots of links to tabletop-gaming industry companies’ websites:

https://www.tabletopdirectory.com/

Daily exercises to get your next game design session off to a creative start:

https://docs.google.com/spreadsheets/d/1EL8_UgBh4VnNFJh6Fa8cnVVqxKtWEKbnTF7IAIN9cZI/edit#gid=0

An extensive list of board game manufacturers:

https://boardgamemanufacturers.info/

Board game designers share their favorite prototyping tools:

https://twitter.com/ProtospielNotts/status/1273293939924230150

10 methods of creating tension in a solo game or a game’s solo mode (video)

Tips for designing your games for a specific audience (audio):

https://www.boardgamedesignlab.com/designing-games-for-a-specific-audience-with-phalgun-polepalli/

Lots of pointers for running a smoother online playtest:

http://www.thegamespeople.co.uk/getting-the-most-from-virtual-playtesting/

Why might a designer exchange a simple rule for one that’s less elegant? A Twitter board game design discussion:

https://twitter.com/PuppyShogun/status/1270400646685097985

A thorough survival guide to pitching your game, from scheduling and preparing to answering questions and tracking your progress:

https://www.dmrcreativegroup.com/post/pitching-survival-guide

A note on the “rules” for new designers to follow—but also when to break them:

https://twitter.com/KevinWilson42/status/1270757552834347011

“So many mistakes have been made, and so many lessons have been learned by other designers. If you don’t play their games, you’re going to waste time making all those mistakes again for yourself.”

— Adam Porter

Making your prototype more appealing for pitches through stock art, example diagrams, decent components, and a how-to-play video:

https://randomskill.games/so-you-think-you-can-be-a-board-game-designer-part-5-presentation/