How to make an animated treasure chest.
1. Select what you want to gain from the chest, for example gold. Additionally, switch the graphic on this event to an empty treasure chest. (Make sure to set the trigger as “action button” (Example 1)

2. You may want to add text to show that you have gained gold/ items (Example 1) Add a “play SE” or “play sound
effect” (Example 1) Add a second page and make the picture
an open treasure chest (Make sure it is the same type of chest) also set the self switch on so that it changes. (Example 2 and 1) Add a control self switch to the second page. (Example 1) Add a text box on the second page to show you that you have emptied the chest and prevent you from gaining the treasure twice (Example 2)
Example 1

Example 2