SC2, PUBG, the new in-progress Unreal Tournament etc. work fine, even on midrange 2015 hardware. You'll get about 55FPS on 2k resolution. Basically, as long as you get a recent GPU, any reasonable i5 or better machine gets game-ready. Steam, Origin and Epic games all work with it out of the box.

And you can if needed reboot to windows and use it as a game-OS for unported games.

Cost-wise, it's a no-brainer for when you enjoy macOS and portable computing, adding a PCIe-TB3 box and a GPU is well below the cost of a dedicated gaming PC. If you wanted a single fixed system, a dedicated PC would be the more economical choice, but economics aren't always the endgame. Especially if you simply enjoy macOS and don't care for hackintosh setups; it leaves you with few options for hardware and this is a nice solution.

> the new in-progress Unreal Tournament

Sadly it's no longer in progress, the last update was over a year ago and the GitHub repo is similarly dead.

Fortnite suddenly becoming the most popular game in the world changed Epics priorities somewhat.

iirc the Unreal Tournament team was the one who made the battle royale mode for Fortnite, so I don't think they're going back to UT anytime soon sadly.

A few demanding-ish 3D games have Mac versions. I have the two Metros for example. Although they were demanding when the nvidia 7xx was new...