For the last few version I’ve been implementing the ability to share game modes. Actually triggering a share was made user facing in 0.20 but the game could load them (with varying degrees of success) before then.
It was a multiple step process because it more-or-less requires a website to exist. For example if you visit this page it includes a link to “try opening in the app”. If you click the link on desktop it will take you back to the same place since that is the fallback page for the sharing link.
An additional feature I developed at the same time as sharing is the ability to embed little game mode widgets in the site.
Another thing I’ve been doing that uses the sharing link is creating YouTube videos of the interesting game modes feature the AI.