Play-via-Data-SMS is one of my favorite features of CrossWords. It's super-reliable, and works between GSM phones round-the-world without requiring any kind of server. Most apps have servers in order to harvest saleable infomation about you or to show ads, but CrossWords is ad-free (and not-for-profit) and so has always supported this feature.
Unfortunately, Google's decided there may be security problems with SMS and is prohibiting most apps from continuing to send or receive SMS (including Data SMS) if they want to be listed on the Play Store. And so I've removed the feature from the CrossWords "variant" that's available there. The feature remains, however, in other variants, including those at:
(The GitHub and Sourceforge variants will install over the top of the Play Store variant without problems. With the F-droid variant, however, you'll have to uninstall your current variant first, losing your games and settings.)
I've also written a data-SMS-forwarding app called NBSProxy. With NBSProxy installed, CrossWords will be able to communicate using Data SMS without the SMS permissions (since NBSProxy has them, and is the one using Android's Data SMS functionality.) Google says that apps whose core functionality requires SMS permissions will be allowed on the Play Store, so NBSProxy should be available there soon. In the meantime, you can get it from GitHub.
Side note: It'd be helpful to know how many people use the Play-via-Data-SMS feature in deciding whether to keep these separate variants going. Would you mind emailing me and letting me know whether you've found it useful?
Thanks!
--Eric