Hi,
if you scroll up a bit there is history of updates and what is coming next.
1. next game version to be released is 0.6.
2. only levels 14-17 are planed to be released with this update, and do to past that is subject to change.
3. There will be Demon that is not mentioned in achievements. And "Special Enemy Variant" which may be more akin to white and red skeleton, nothing was spoiled for this one, as it should remain.
Hope this helps, good wind