Disclaimer: Now, stop, please. I know of Emacs manual, tutorial and all the other built-in docs. Stop telling me to use them, because I won't, thank you.
I'm recently learning Emacs - I reached high proficiency in Vim and I thought about learning it's competitor, just to feel comfortable with them both. I like Lisps, so that's another motivation.
I had a hard time in the beginning. I was missing tabs (elscreen) and many other features and familiar keybindings, so I installed Evil and made my own mappings. Now I can live with Emacs, but I realized that while I learned a bit about how Emacs works and how to script it, I completely neglected the idea of feeling comfortable in raw Emacs! I probably could M-x and M-: my way on Emacsen other than mine, but that's hardly the point :)
So, is there something interactive one could use to learn Emacs editing basics?