Go to the store and look at what is out there first. If you already have a design, could it stand on the shelf with the other products? If you don’t, try to design something new that could be on the shelf with the other products.
— Brad Ross
Praise doesn’t help me make my game better, it only serves to reassure me that I make awesome decisions and that hampers my ability to change those decisions later.
— Chevee Dodd (@cheveedodd)
[Push] a game’s limits when the game seems fine.
— Olivier Lamontagne
If you never make mistakes, you are not working on challenges that move you further. And that’s a BIG mistake.
— Reiner Knizia (@ReinerKnizia)
I think the methods and tricks for designing a card or board game are very similar to those used by novel writers, the main difference being that we game designers skip the hardest part: the actual writing.
— ~ Bruno Faidutti (via whyidesigngames)
I sometimes think of games as cars: they need to have an engine (the core mechanic), a steering wheel, gear shift and gas pedal (ways for the players to set their speed and direction), and the car body (flavor and theme). Also, if possible, a destination. The perfect game like a great car has all the parts fitting well together, and that’s what hopefully we are all trying to achieve.
— Andrea Chiarvesio

The Strategy Game Designer’s Constitution contains some “golden rules” for design, considerations for giving games strategic depth, plus a good list of potential end-game and victory conditions:

http://www.leiavoia.net/pages/docs/Strategy_Game_Designers_Constitution.pdf

Here’s the handy, pocket-sized Strategy Game Designer’s Cheatsheet:

http://www.leiavoia.net/pages/docs/Strategy_Game_Designers_Cheatsheet.pdf

Scoring simply as performance evaluation or identifying winners is not interesting. You have to actually care about the game for winning to be meaningful so if you’re going to score, the way you do it has to validate the game experience. How it’s done matters a lot.
— Chris Farrell (@cfarrell317)
Good playtests lead to changes in your game. The best changes are the ones that make you wonder why it wasn’t that way in the first place.
— Samuel A. Liberty (@SA_Liberty)
Iterate, but have a goal. Games can meander for years without one.
— Matt Leacock