Awesome! LTI stands for Learning Tools Interoperability, and basically there are established protocols (http://www.imsglobal.org/lti/index.html) for them so they can be easily integrated into any education system.
The following link has all the basics on creating an LTI app and how to interface it with Canvas. https://www.eduappcenter.com/docs/basics/index
It would be ideal if it could:
1) automatically create an account in CodeCombat based off of the user id in Canvas.
2) reference that user id to bypass login for CodeCombat material
3) be able to pull one level at a time on a page https://www.eduappcenter.com/docs/extensions/content (housed in an iframe) via rich content editor https://www.eduappcenter.com/docs/extensions/canvas_wysiwyg and/or by creating a direct url link in a module https://www.eduappcenter.com/docs/extensions/canvas_link_selection
4) Determine completion of level and assign a grade into the gradebook https://canvas.instructure.com/doc/api/file.homework_submission_tools.html
I'd love to see this happen. I could literally let my students play games for credit.
Also, Canvas is free and open source, so you can easily build and test it by signing up for a canvas account. https://canvas.instructure.com/register_from_website?lead_source=Free_For_Teacher_Request