Mental exercises

Do top players do puzzles, crosswords or other stuff other than chess to stay in 'form'?

I think that, when it comes to GMs, IMs and so on, they spend most of their spare time around chess (analyses, games etc), never touching one of those brainy puzzles or other games that are supposed to improve your brain function (unless they do just for fun, that is). I may be wrong, but the instinct tells me I am probably right. 
Definetely playing 'clever' games is much better for the higher functions of the brain than killing zombies on your console or pc! (on the other hand killing zombies can be highly entertaining)  

Funnily enough competitive, fast paced shooter games have been proven to significantly improve one's ability to do lots of useful things... For instance:

keep track of multiple pieces of information, form imaginary maps and scenes with moving parts, exercise predictive, stratigic and tactical thinking, reaction speeds and most significantly, concentration. 

Doubt this would be more helpful than just Chessing it, like the reply states, but don't underrate video games! More and more data is being found about the positive impact on the brain caused by healthy levels of gaming. 

Try thinking of a new color.