More polish, hide unfinished chapters/levels

levels/unused/pull-push

@@ -0,0 +1,51 @@
+title = Helping each other
+cards = checkout commit-auto reset-hard pull push
+
+[description]
+
+The events and timelines you see are always only what your own time machine knows about!
+
+Of course, time agents don't have to work alone! Here, your sidekick has already prepared a merge for you! You can use the "pull" card to transfer it to your own time machine.
+
+Then, add another event on top (what does Sam have for dinner?), and `push` the result, to transfer it back to your sidekick!
+
+You can only ever manipulate things in your own time machine (the one on the bottom).
+
+[setup yours]
+
+echo "Just woke up. Is hungry." > sam
+git add .
+git commit -m "The beginning"
+
+git checkout -b pancakes
+echo "Had blueberry pancakes with maple syrup for breakfast." > sam
+git add .
+git commit -m "Pancakes!"
+
+git checkout -b muesli main
+echo "Had muesli with oats and strawberries for breakfast." > sam
+git add .
+git commit -m "Muesli!"
+
+git checkout main
+
+git push -u sidekick main pancakes muesli
+
+[setup sidekick]
+
+git checkout main
+git merge pancakes
+git merge muesli
+
+echo "Had pancakes with strawberries for breakfast." > sam
+git add .
+git commit -m "Let's make this breakfast compromise" --author="Sidekick <sidekick@example.com>"
+
+[win sidekick]
+
+# Below main's parent, there is a rhombus:
+git rev-parse main^^ && test "$(git rev-parse main^^1^)" = "$(git rev-parse main^^2^)"
+
+[congrats]
+
+In reality, in many cases, a lot of time agents work together to build a really good future together! :)

levels/unused/remotes-add

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+title = Adding a remote
+cards = checkout
+
+[description]
+
+Let's work together with others! Your friend has their own repo at the URL `../friend` - you can add it using
+
+    git remote add [name] [URL]
+
+where `[name]` is an arbitrary, short name you pick for the remote.
+
+When you've done that, you can get all commits from that remote using
+
+    git pull friend
+
+There's a letter for you!
+
+[setup]
+
+git remote remove friend
+
+[setup friend]
+
+echo "I'm really committed to our friendship! <3" > love_letter
+git add .
+git commit -m "Write a letter"
+
+[win]
+
+# Add a remote that points to ../friend.
+git remote -v | grep '../friend'
+# Pull from the remote.
+git show HEAD:love_letter | grep committed

levels/unused/remotes-delete

@@ -0,0 +1,23 @@
+title = Deleting and renaming a remote
+cards = checkout
+
+[description]
+
+Here, you already have two remotes configured! You can list them using `git remote`.
+
+[setup]
+
+git remote rename friend frend
+
+[setup friend]
+
+[setup enemy]
+
+[win]
+
+# Rename the remote with the typo (using `git remote rename [old name] [new name]`)
+git remote | grep friend
+# The remote with the typo is gone.
+! grep 'frend' <(git remote)
+# Delete the remote you don't want to keep (using `git remote remove [remote]`)
+! grep 'enemy' <(git remote)

levels/unused/split

@@ -0,0 +1,26 @@
+title = Split a commit!
+cards = checkout commit reset-hard reset add rebase-interactive rebase-continue show
+
+[description]
+
+Here, both changes happened in one commit! Split them to be in two commits instead.
+
+[setup]
+
+echo something > file1
+echo something else > file2
+git add .
+git commit -m "Initial commit"
+
+echo this should happen first >> file1
+echo and this should happen after that >> file2
+git commit -am "Both together"
+
+echo this is some other change >> file1
+echo this is some other change >> file2
+git commit -am "Something else"
+
+[win]
+
+test "$(git diff-tree --no-commit-id --name-status -r main^)" = "M	file2" &&
+test "$(git diff-tree --no-commit-id --name-status -r main~2)" = "M	file1"

levels/unused/steps

@@ -0,0 +1,23 @@
+title = One step after another
+cards = checkout commit reset-hard add
+
+[description]
+
+Sometimes, you might want to record the order in which things changed, instead of making a single commit.
+
+What happened here? Make two commits from the changes (using the "add" card), in an order that makes sense!
+
+[setup]
+
+echo something > file1
+echo something else > file2
+git add .
+git commit -m "Initial commit"
+
+echo this should happen first >> file1
+echo and this should happen after that >> file2
+
+[win]
+
+test "$(git diff-tree --no-commit-id --name-status -r main)" = "M	file2" &&
+test "$(git diff-tree --no-commit-id --name-status -r main^)" = "M	file1"