In a regular Add-A-Gram, each word in the chain is an anagram of the previous word plus one additional letter. It is possible to solve them from any entry point, and then work forwards or backwards from there.
I've decided to add encryption to the Add-A-Gram so that it can only be solved incrementally from the beginning. There is a logical and consistent way each clue is encrypted. As you go, there will be no doubt that you are on the right track.
Given the nature of this puzzle, I ask that solutions be withheld until they are complete.
Here is the definition for this Encrypted Add-A-Gram chain:
a constant speed in vygpvkgvj qh kvu mkpf in c lwmknquu eneettiean dksehcrie in a ccrxg adquev in pgkvihp in ytuzhsg in vyiexq-vyieh gh ztf oapu in snwpy in nyckxefil zgdfrsrm qkjos in ezaltersw in hee jzw eqxsvrtrk ir vothjigawr in sbaqkuoy wiekigkoqhviw in nexs in tsyttqak kz e hwvwgbov ssi lrgljse
Happy Encrypted Add-A-Gramming!