DISCLAIMER: IS MY PERSONAL OPINION AND DOES NOT CONSTITUTE LEGAL ADVICE. I AM NOT RESPONSIBLE FOR ANY DAMAGES DIRECTLY OR INDIRECTLY CAUSED TO YOU.
Edit: OK I am now a “Registered Gameworks Developer” and I also found the Nvidia GameWorks Logo & Brand Guidelines: https://developer.nvidia/gameworks-logo
Ah, just imagine a world without lawyers…
I am not a lawyer but it appears Nvidia contributions fall under the UE4 EULA at https://www.unrealengine/eula particularly:
*
" b. Distribution to other licensees - You may Distribute Engine Code (including as modified by you under the License) in Source Code or object code format, or any Content, to an Engine Licensee who has rights under its license to the same Version of the Engine Code or Content that you are Distributing.
Any public Distribution (i.e., intended for Engine Licensees generally) which includes Engine Tools must take place either through the Marketplace (e.g., for distributing a Product’s modding tool or editor to end users) or through a fork of Epic’s GitHub UnrealEngine Network (e.g., for distributing source code)."*
However the Nvidia contributions to UE4 to me still “incorporate the NVIDIA GameWorks SDK or portions thereof” (see above) so unless there is a particular waiver that Gameworks in Unreal Engine is covered by Unreal Engine EULA and NOT also Gameworks EULA, the Gameworks EULA still applies.
If someone from Epic and/or Nvidia can clarify these issues that would be great.
Personally I think it’s just a matter whereby Nvidia contributions and UE4 development in general is moving very fast that on the legal side they specify such things but on the “practical” side certain things haven’t caught up like including Nvidia splash screen assets in the Nvidia forks of UE4.
For example, Epic requires (from their EULA)
- You agree to retain and reproduce in all copies of the Licensed Technology the copyright, trademark, and other proprietary notices and disclaimers of Epic and third parties as they appear in the Engine Code and the Content.
You agree to place the following notices in the credits for any Product (replacing xxxx with the current year):
“[Product name] uses the Unreal® Engine. Unreal® is a trademark or registered trademark of Epic Games, Inc. in the United States of America and elsewhere”
“Unreal® Engine, Copyright 1998 – xxxx, Epic Games, Inc. All rights reserved.”
No other license or right in the Epic Trademarks is granted under Agreement. All use of the Epic Trademarks will inure to the sole benefit of Epic. You agree not to engage in any activity that could tarnish, dilute, or affect the validity or enforceability of the Epic Trademarks or cause consumer confusion or diminish any goodwill relating to any Epic Trademarks. If you wish to make further use of the Epic Trademarks, please go to https://www.unrealengine/branding-guidelines-and-trademark-usage. *
A straightforward win-win for Nvidia, Epic and game developers is simply to have the right assets to show Nvidia Gameworks, UE4, etc. at the start of the game. It also shows that your game has all the latest cool fancy game technology too 
For Unreal Engine at least it is a bit clearer: https://www.unrealengine/branding-guidelines-and-trademark-usage
As a former(?) (2D) graphic designer, to me, it appears Unreal Engine covers all the bases very well for logo, brand, trademark usage in both the EULA and the branding guidelines as above including logo use, etc. You can also download the official animated “Powered by UE4” video.
Game developers new to Unreal Engine I imagine will have to peruse the Unreal Engine EULA and Brand Guidelines and if you have anyone on your team with 2D corporate design or ad agency experience they should be able to advise and/or implement things accordingly.
As for Nvidia, they have the branding guidelines for apparently mainly their hardware partners (board manufacturers etc.) at ://uk.pforce.nvidia/Brand/Brand_Guidelines/NV_Partner_Co-brand_Guidelines.pdf
However, I can’t seem to find the Gameworks branding guidelines (EDIT: I FOUND SOMETHING, SEE ABOVE), maybe everything will be made clearer at the Nvidia Registered Gameworks Developer side of things as at: https://developer.nvidia/gameworks-registered-developer-program.
As I made a VXGI video maybe I’ll just sign up and report back .
Edit: Found it… So at least we have the UE4 EULA and Brand Guidelines and the GameWorks EULA and (some) Brand Guidelines.
For the legal aspect, as a game developer or game development company, looks like you’ll have to consult a lawyer if you want to cover yourself accordingly.