It isn’t the architecture which makes it difficult, it’s the runtime environment. The kernel itself provides certain system calls, and these can be the same across a large number of platforms. However, the libraries and linking and support within the environment itself can be vastly different across platforms using the same architecture. Android and Linux in general mostly have no portable C/C++ applications unless you both recompile and also edit code for completely different libraries. Android is the biggest example because it has a Linux kernel, but you can go to a finer detail and find that something like Ubuntu 14.04 and 16.04 applications won’t necessarily run on both without supplying missing dependencies which conflict with the existing library versions. Practically no application on 14.04 would run directly on 18.04 without significant changes, and they are both Ubuntu. Surrounding environment is why I say it would probably be difficult. Games tend to have more dependencies than special purpose programs.
If you can build the Unreal engine, then your chances go up. I remember some people talking about getting Unreal going, and I think it was a success (but I don’t remember where it was discussed…somewhere in these forums). What I’d suggest is by starting a thread on Unreal engine (such as git source locations and READMEs, so on). When that is established it would become worth talking about specific games compiled against Unreal. If you can add a link to something you’ve built then we could try that on a TX2.
If you’ve built a game depending on Unreal I’ll suggest running “ldd” on it and listing those so we can search for what packages provide those.