feat(outro): expand the heck out of it

src/outro.md

@@ -1,6 +1,40 @@
 # Outro
 
-## Thank You
+Thank you so much for reading and going through _Building Games with DragonRuby_. I hope you continue to use DragonRuby Game Toolkit and make awesome games. [Jump in the Discord](https://discord.dragonruby.org), and share what you've made. The community would love to see it and will happily answer any questions you have.
+
+## Make _Target Practice_ Your Own
+
+We made _Target Practice_ together, and now it's time for you to make it your own. How can you change or expand upon it? What would take it to the next level? What would make it more fun?
+
+Here are some ideas for what you could do to put your personal stamp on it:
+
+- Make the targets move
+- Make the targets shoot fireballs that you have to dodge
+- Replace the sprites with your own
+- Make your own music track and drop it in
+- Build out waves of enemies that fly in and attack you
+- Make it so the dragon can fly around a level instead of stay in one screen
+- Add a narrative introduction
+
+## Say Thanks
+
+Say thanks in [the DragonRuby Discord](https://discord.dragonruby.org) or on [Mastodon](https://mastodon.gamedev.place/@brettmakesgames). It would mean so much to me know that you've read the book. The website version of this book has no tracking. My success metric isn't number of views. I'll only be able to measure the success of this book through community and connecting. Share what you've made!
+
+If you really want to say thanks, [buy me a coffee](https://www.buymeacoffee.com/brettchalupa) by sending me a small tip. Financial support means the world and helps me continue to make free resources like _Building Games with DragonRuby_.
+
+## Want More?
+
+Writing a book about making games is challenging to scope properly because games are so complex. We built a pretty simple game that covered a lot of the core concepts of making games, but there are _so_ many directions a sequel could head in.
+
+A second edition of the book could deep dive into making a shmup with enemy waves and bosses. Or we could build an entirely different game, like a platformer or a dungeon crawler.
+
+But I _need_ to be sure people want a follow up book where we build a more complex game using DragonRuby Game Toolkit. Let me know if you'd like to see a sequel in [Discord](https://discord.dragonruby.org).
+
+## Extra Credit
+
+You'll find bonus chapters after this outro. They're one-off deep dives into specific topics, from the mindset that's required to make games to how to back up your game's source code. Check them out and see what you can learn!
+
+## Gratitude
 
 A big thank you to the DragonRuby community. This book would not have been possible without their support and guidance.