Greetings, 

I am unable to start the game I bought , although I can play to the demo. I have OS X El Capitan (10.11.6) and I can't update, my Mac is an old model. I have v 1.2.

Can you help me please ? 

Thanks. 

P.S : Sorry for my english, it's not my native language. 

We're aware of the issue, but it unfortunately isn't anything on our end. For more specific info, please check the top comment chain on this post: https://sswk.itch.io/signed-and-sealed-with-a-kiss/devlog/97943/version-13-update-preview

Each purchase on itch.io includes a free Steam key, which we recommend redeeming and using until version 1.3 is released, as it is a consistent workaround for the codesign issue. If the game still can't launch on our next update, we'll be looking into alternate methods to launch the game or perhaps crowdfunding by selling leftover physical goods from our titles to afford a Mac to manually develop/test future game builds on. Apologies for the disappointing answer. :(