RETRACTLE

A paper has been accidentally retracted! It's on you to repair the damaged document and make sure it's restored into the archive.

• Guess a word: it is restored everywhere it appears in the paper, in all its forms (observe, observed, observing; galaxy, galaxies).
• Restore every word of the title to win. Each black bar shows how many characters it hides, and the guess box counts what you type the same way.
• Small words (the, of, and, is, with…) were never redacted. Numbers were.
• Formulas are shown as in the paper. Their words and their longer numbers are redacted too; symbols, short numbers and one-letter variables are not.
• Figures are retracted too: each comes back once you've restored 40% of the words hidden in its caption (one without a caption, when the game is over).
• Click a guess in the list to highlight its places, and again to go through them one by one; a word you guessed before, typed again, does the same with Enter. The score shows how much of the paper you've restored: the share of its black bars your guesses brought back.
• A new paper every day at midnight; « and » beside the puzzle number take you to earlier days' papers. The papers are famous, well-loved astronomy papers from arXiv; none of them was really retracted.

Retractle is inspired by Redactle, which does this with Wikipedia articles.