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
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
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