vimhjkl

vimhjkl drills you on Vim until the commands become muscle memory. It runs inside real Vim, hands you an editing goal, and scores your keystrokes against a verified-optimal solution, then schedules your weak spots for review using spaced repetition. Free and MIT licensed.

It's a trainer, not a cheat sheet. Five modes cover learning, blind recall, targeted practice on your worst skills, and flashcard review, across 61 lessons and a couple hundred hand-vetted challenges. Because the optimal solutions are replayed in actual Vim, you can't fake your way through with sloppy keystrokes. Install is trivial through Homebrew, the AUR, or source.

The closest paid option is vim-adventures, the browser game that runs about 25 dollars. vimhjkl is free, lives in your terminal, and grades efficiency, not just correctness. The free alternatives, vimtutor and vim-be-good, are lighter and don't track your progress over time.

The catch: it's solo-maintained and early, version 0.4, and it asks for commitment. This is a daily-reps tool, not a quick reference. If you'll actually do the drills, it's the best free option going.