User blog comment:Yami riku/Merit Point Tests/@comment-29711200-20161120063232/@comment-25646419-20161120070507

For the PTR currently, you can obtain Town Points by:
 * Purchasing the Steam version of the game
 * Purchasing Town Points directly from the in-game shop
 * Purchasing a promotional bundle which contains Town Points

All of these options use real life currency! At this moment, newer items can only be purchased with Town Points. The Holiday Theme, Voxel Theme, Apocalypse Theme, and Winter Theme bundles can only be purchased with Town Points.

Achievements were changed so they give out Merit Points instead of Town Points.

Not sure which direction they plan on heading with this. Like will there be future items which can only be purchased using Town Points? Why make the bundles which have been out for ages not be accessible by paying in Merit Points?

Hopefully, they'll give more answers soon.