There really isn't any 1 single answer. Rather there are multiple distros (specific ones) which are all currently 'modern enough' to use for gaming. The main underlying criteria being that they can install reliably "new enough" packages. And without running into significant issues.
Here's a shortlist (not exhaustive - there are other ones too)
* SteamOS - if you want it like that
* Fedora - either traditional version or silverblue
* MODERN derivatives of ubuntu that are based off the most recent 6 monthly point releases (i.e. 23.04 and forwards, so no, not any LTS based ones)....
* Arch linux based distributions (and not Manjaro)
Of course with extra work you could use something else entirely. For example ones like gentoo, or void linux. Or many others. But fundamentally maintaining a distro properly (and to a high degree of polish). That takes work. So by sticking to the main distro(s). Then you are avoiding and dodging a lot specific grief. That they patched or sorted out for you already. Not to need to take individual steps on your individual machine(s). When the vanilla upstream software projects are releasing things with bugs in them (or is badly packaged, or is too cutting edge new features that are not quite ready yet to work with the other libraries, causing conflicts etc.).
If you want to include more options, you can also think to ones like suse tumbleweed (for example). But the main other criteria that I did not mention yet: are inclusion of proprietary codecs and proprietary drivers. For media to work and not be broken. So any "fully free" distros tend to be more trouble in that respect.
So, (for example): you could also easily add:
* Debian
To this list, but only if you download and install the version with all the non-free packages. For which there is some special ISO (or not-quite official installer). Then should be fine.
In terms of how to narrow down further (in a vacuume) - well arch is more difficult to use. And more overheads / legwork to keep updated properly. Or fix broken updates. However in exchange for that it has a better / best possible 3rd party packaging system included onto it.
Wheras both Fedora and Ubuntu use more traditional binary pkgs systems respectively. Whereby it's harder to make and contribute or distribute your own pkgs onto those platforms. But in exchange they are generally easier to update, more reliable (against unexpected breakages). Easier to deal with any potential pkging conflicts. And just more popular so finding support help answers online is also easier.
One caveat to that is: For whichever distro you choose. Then arch wiki is a great general and very helpful documentation resource. To lookup general linux technical matters. And remains helpful regardless of whichever specific distro you happen to be on.
