I managed to unlock the Game Modes menu in Offline Mode.
I also added back Ghost Mode to the menu but don’t expect anything playable from it.
Contracts Mode menu is still locked as expected and even if I manage to make the menu interactable in Offline Mode, it will be pointless since the mode is inherently for Online Mode.
Though I still think it’s worth investigating to see what happens if the menu is interactable in Offline Mode and see if Contract Creation is still functional. Just for curiosity.
The menus are probably going to be empty but I have noticed there were lots of custom contracts stored locally in HITMAN 2 so I might check over there when I have time.
EDIT: As expected, it’s full of empty menus and Kevin_Rudd is right that Contract Creation doesn’t work because it’s not even an option that you can select.
Sniper Assassin Mode menu is just empty. It probably only calls the menu if the game is in Online Mode.
The remains of the Ghost Mode menu.
Inviting a player does nothing, of course.
Selecting a suit just shows an error.
But the game rules and eliminate targets’ description are still readable and the briefing is still viewable.