Tip for new designers: your first half-dozen games (at least) are going to be terrible. Lower your expectations, iterate quickly, and be prepared to throw them out.
Peter C. Hayward
A key tool in developing a mature design is addressing those lingering feelings you have as a player. Isolate and fix those 1% kinks.
Every theme is pasted on. Our job is to make that paste as strong as possible.
Try to play your game as quickly as possible. Find out whether your core idea has the spark to be interesting. Don’t think about it; try it. Forget about balancing, artwork and UI. Instead try to define what you consider to be the core mechanisms, and test whether they are fun at all.
Asger Sams Granerud
Is it your responsibility as a game designer to create a system where it is difficult to cheat? This conversation has people flip flopping depending on which side they sympathize with, the player or the designer. But since this post is directed at designers there should be no defensive stance on this. I will say
Prototype everything! You never know what works in the real world if you only design in your head. A failed test may result in a successful fix for something else.
Make it smaller. Then make it smaller again. Until you can’t anymore.
John du Bois
Those nights when your brain just won’t close up shop and pure nectar is pouring through.
At what stage is a game ready for play testing? When you can’t find a way to break it yourself.
If your dreams don't incite you, you're not ready for bigger things.