It is a good Monday Mashup because you can take the Titanic and use its themes in a variety of games and genres.
For my choice?
Just to show the diversity of the setting, I will steal from an old computer game, Ultima Underworld II. Imagine a flying fortress like Killorn Keep, created by a powerful arrogant wizard as the ultimate in travel and living, a way to traverse the land and slowly get from place to place. An impregnable, unstoppable floating fortress.
The PCs job is to find a way to provide the metaphorical iceberg. Hired by sorcerers guild jealous and envious of the wizard’s power, they would like to see his hubris repaid in kind.
The trick is for the PCs to board and discover the secrets of the Keep, and find a way to end its flight–without losing their own lives.