Strong induction / lt world first draft

[kvanvels]

First draft of strong induction world.

[joneugster]

Is this ready for review? If so, it would be @kbuzzard 's review that would be needed.

(Otherwise, could you mark the PR as "draft" until it is ready)

[kvanvels]

Hi, I think the ball is in @kbuzzard 's court. I think it is ready for a review but he doesn't have the time to review it. I think this will probably die on the vine.

[joneugster]

Hi, I'm afraid this might not be moving anywhere. As I feel the authority over this game's content is in Kevin Buzzards hands, I don't feel like I should accept these PRs myself.

I would suggest the following: Create a new game "NNG-community" or something (a new github project) which contains the new worlds from this PR and the next one.

Then give me a text on Zulip so I can:

• move your new repo to `leanprover-community/NNG-community (optional; if desired)
• ensure the game gets displayed on the game server

This way yous could have the review authority to add more content and people could play it and we don't need to depend on reviews here!

Would that sound reasonable? Sorry for how slow things move...