What is the type of puzzle where it is set up like a crossword, but instead of clues each box has a number?

JillandJack: What is the type of puzzle where it is set up like a crossword, but instead of clues each box has a number?
And each number represents a different letter, so you have to try and figure out what number all 26 letters goes with so you can create words & fill in the puzzle? What is it called and what sites can I play it for free? Thanks!

Answers and Views:

Answer by Person
I’m sorry, I’ve never heard of that.

Answer by David Presents
I’m not sure, but I believe you are describing an acrostic. You can solve acrostics for free at www.acrostics.org