Braid Cheats

Unlock Final Star and secret ending
Throughout the game, there are 7 secret stars. If you collect them all, the 8th and final star will appear in the last level; when this happens, some of the switches in the level will become immune to time manipulation, allowing you to reach the star as well as changing the outcome of the chase.

Unlock World 1 and the Epilogue
In the house (level select area), there is a broken ladder that leads to the attic. To repair this ladder, you must find all 72 puzzle pieces and assemble each world's jigsaw puzzle. Once this is done, you may climb up and enter the door to World 1. After beating World 1, you will be taken directly to the Epilogue, which you can return to at any time after its completion by walking left from the title screen, into an offscreen alcove.

Hidden Texts in Epilogue
Aside from the last, each room in the Epilogue has at least one object that you can stand behind. If you have the red book on that screen open and the text of it is displayed in the air, standing behind these objects in the proper location will cause a sound to play and the text to change, revealing more information. If you open a green book, the red book will close and the text will disappear, so you will need to use time manipulation to see all 4 of these secret writings.