This t-shirt stylishly displays the principles every game designer should live by:

1. I will playtest other designers' games
2. I will thank playtesters in the credits
3. I will be inspired by, but not COPY, other designers' games
4. If co-designing a game, I will put in as much effort as my partner
5. I will be honest with my feedback
6. I will not get defensive when hearing playtester feedback
7. I will wait until the end of a playtest to provide feedback
8. I will not redesign another designer's game
9. I will always provide feedback even for a genre I don't enjoy
10. I will end a playtest if it is not going well or is dragging on too long

The perfect addition to any game designer's wardrobe.