I would just talk to your kid and listen to his feelings and wants. What does he enjoy about Roblox? Can he find that enjoyment with some other games? Does he understand that its not a punishment, e.g. it’s not anything that he did and that you aren’t blaming him? Sure, you can suggest a few alternatives and they might take and be fun, but you’ll need to be attuned to his feelings around what he might see as a punishment for something that he did so that he doesn’t internalize it and hurt the relationship you have with him.
I would just talk to your kid and listen to his feelings and wants. What does he enjoy about Roblox? Can he find that enjoyment with some other games? Does he understand that its not a punishment, e.g. it’s not anything that he did and that you aren’t blaming him? Sure, you can suggest a few alternatives and they might take and be fun, but you’ll need to be attuned to his feelings around what he might see as a punishment for something that he did so that he doesn’t internalize it and hurt the relationship you have with him.