User blog comment:Master Sima Yi/Assassinews 03-12-'14 — New Assassin's Creed in Victorian London leaked/@comment-94.59.29.21-20150207023215/@comment-94.59.29.21-20150207113313

Ubisoft Montreal uses a modified CryEngine for the Far Cry series. They could have used that for a change. Also,  not much third person action/adventure "stealth" games use Frostbite. Most games using Frostbite are EA's Battlefield and NFS. I guess UE4 would be good.