As I mentioned a few weeks ago, the BBC has just 'opened the flood gates' to CDX for a limited time to iron-out and debug issues with its technology that restricts access to UK IP addresses only. Therefore, this may be your last chance to play the game if you live outside the UK.
Update: After much on-again, off-again with the BBC restrictions allowing only UK players to experience this game, the very kind, talented and generous folks at Preloaded are now hosting the game themselves! So, if you are located outside the UK and wish to play this fantastic piece of work, you now may do so. Please visit the CDX review page for the link.