That's true that games are either downloaded or played through a disc, but most kids and teens nowadays play games that are meant to be played fully and exclusively online as they are massive multiplayer experiences. If your kids or grandchildren scream that they can't pause the game when you call them over for dinner, this is probably the kind of game they are playing.
That said, as was said before the Internet on the ship won't provide a good online gaming experience, even if you purchase Surf and Stream, because it is a satellite connection. Games require small packets of data to be sent back and forth very quickly to update what's going on in the game. Satellite connections, however, are built to sent huge packets of data but less frequently due to the time it takes for the signal to go back and forth. It is the exact opposite of what you'd like for online gaming because it generates extreme amounts of lag.
And then there's the issue of connecting to the TV. I used to travel a lot for work and bring my PS4 with me to plug to the hotel's TV, but in each hotel I had a different problem:
- the way the TV was wall mounted blocked access to the HDMI ports;
- the remote control in the room lacked controls to change the input source and the TV had no buttons on it;
- the TV was a special type called Hospitality TV made for hotels where every port, if there's any, is disabled;
- no power outlet close enough to the TV;
List goes on. If they are cool playing offline, perhaps gaming solutions for which a TV is optional would be better, such as an iPad, the Nintendo Switch, a Steam Deck, a PS Vita or anything of that sort.