I want to say the equivalent of
I can already tell (understand) that game X is (going to be) harder than game Y.
For instance, I've already beat game Y. And even though I've only just started playing game X, I can already tell it is going to be harder than game Y. That's what I'm trying to convey in a sense.
I know that to say "game X is harder than game Y" you would say:
But I'm unsure how to add on "I already know/understand/can tell that.."
My best guess is something like:
But I'm not sure if that is right or if there is a better way to say it.