I've successfully added Scrappy Cat, a game I've previously released on web and mobile, to Facebook Instant Games. This basic integration took about an hour, but hopefully with these instructions a lot less:
1. Add this code to your game, at the point you want the game to show:
pcall(function() FBInstant=require "FBInstant" end)
if FBInstant then
print("Loading screen removed")
print("FBInstant not loaded")
2. Export the game to HTML5 with the "Facebook Instant Game" checkbox ticked:
3. Go to https://developers.facebook.com/?advanced_app_create=true
. You may have to open a Facebook dev account if you haven't already.
4. On the "Add a product", choose "Instant Games / Set up"
5. Fill in the details about the game under "Instant Games / Details". The images generated by Gideros should help this process.
6. Go to "Web Hosting", zip up the contents of "package" from your exported project. Once uploaded click the star to "Push to production".
7. Go to "App Center / Details" and click "Web Preview" to test the game. To test on mobile, open the Facebook Messenger app on mobile (with your developer account) and search for your game name.
8. Once you are happy with your game, and make sure ALL monetisation is in, go to "App Review" to submit the game to Facebook.
Hope this guide helps to get started on Facebook Instant Games. Look forward to seeing your instant creations!