Existing games BUT allowing to host your OWN SERVERS!! and modding.
I would put in that list:
Sea of Thieves -> to play only with friends (no PvP)
Battlefield <X> -> to mod and fool around with my friends
Overwatch -> to train, mod, etc.
Star Citizen -> aside from the usual "when the game will be released" let us run our little servers!!
I am sure I am forgetting obvious ones in this list...
Please make games "hostable" and "moddable"! <3