Hello guys!
When they say “… a modified version of Unreal Engine 4 was used”:
1) … what does that mean?
2) … which has been modified
3) … how was it modified?
4) … why was it modified?
5) … can I modify it?
For example, Days Gone: “… the game uses Unreal Engine 4- a modified variant of the game …”
It means exactly what it says. They have modified/changed (in some way) an aspect of the engine to better suit their game/requirements. The changes can be minimal or significant. The source code for the engine is available on GitHub; you are free to change anything you want. There are many reasons to modify the engine, from feature-requirement to performance optimizations, or changes to the renderer to achieve a stylistic impossible otherwise. What precisely the developers of Days Gone have done I can’t answer, but it’s very common (modifying the engine). Having the source code available gives you this freedom and it’s awesome.
My guess they did extra optimization to achieve superior performance on PS4. The question is… isn’t PS4 SDK optimized enough already?