If we go a bit off-topic for this time and look back to past everyone who plays WW2 RTS games must know Blitzkrieg franchise by Nival, last game came out in 2007.
Now 7 years later
Blitzkrieg 3 as F2P with SP campaign microtransactions...
It will use licensed Unity engine not their own updated Enigma engine anymore, why ?
Good question, do they have spare money to update and develop own engines and games also ?
What for if there are at least tens of equal ones and perhaps a lot better ?
Every developer must know that its long and expensive process which costs large amount of time and money. Sure that engine license cost money also but if you have good and capable developers what Best Way and DMS are and time to developing game-content only the final results can be really remarkable.