Nobody would believe in the beginning of 21 centuries, that all event on the Earth sharp-sightedly and is watched closely by beings more developed, than the person; that while people were engaged in the affairs, them investigated and investigated. With infinite complacency people on all globe, borrowed with the affairs, assured of the power over a matter scurried about. And meanwhile through a space chasm to the Earth beings with advanced, cold, insensible intelligence looked eyes full of envy, and slowly, but truly developed the plans hostile to us...
I'm not too familiar with UE4. How hard will it be to convert existing assets?
Meshes - only FBX (no PSK or PSA support). SpeedTree and Scaleform to UE4 not implemented (yet). UE4 is good engine, but... "beta".