From the introduction: Welcome to Yesterday’s Tomorrow, a retro sci‐fi roleplaying game. I designed this game for Ro Watts because she asked me for a steam punk game. I told her, "You don’t want a steam punk game; you want a game about how the past thought the future might be." I said this because she loves movies like Sky Captain and the World of Tomorrow and games like Bioshock. Both that movie and that game aren’t steam punk, but \ they are about a speculative future. A future from the past’s point of view. And so, this game is about just that: how the past thought the future would look like. But it’s also about a little more. I talked with Ro and found out exactly what she liked about those kinds of stories. After our talk, I discovered she really liked four key themes. The first was Action! She loved the high danger and suspense she found in those stories. The second was Science! She loved the technology people from the past thought we would come up with. The third was Mystery! Ro loves Victorian mysticism and so we had to throw in some of that. And lastly, Ro loves Romance! Characters like the roaring ‘20’s dilettante and the Victorian Adventuress were high on her list, so we had to include something for them. From there, I just made stats for each of the things Ro loved and provided a way for the players to create a character based on those four themes. Then, I threw the game at a few game design folks I respect and admire and found out what they thought of it. They gave a few suggestions and the game really started taking shape. And so here is Ro’s game. We hope you enjoy it.