Outing myself as a parent of young kids here, but I have been genuinely surprised how good Hypershot on Roblox is. It reminds me of Unreal Tournament a lot and is really easy to play, I've been hooked for a few weeks. It cuts everything down to the basics like UT without all the bells and whistles modern AAA games have. Oh and it's totally free (but with all the monetization attempts Roblox games tend to have, though they aren't necessary to play even at a high level).