NAME Wooden Block Puzzle Game app. WHAT IT IS A clever, easy and addictive game in which you have to fit wooden pieces on a puzzle board. HOW MUCH Free.

You know about puzzle books---books of puzzles, or books that are themselves puzzles. But then there's Codex Silenda ---a gorgeous, wooden book of brainteasers that is itself a multi-part mystery.

and fabricating intricate wooden puzzle boxes. There's one I made that was a 5,000-move box, but it took so many moves it would just wear itself out. before you could really open it successfully.

Listeners who submit correct answers win a chance to play the on-air puzzle. Important: Include a phone number where we can reach you Thursday, Feb. 9, at 3 p.m. ET. Will Shortz ...