I'm not sure if this counts as gameplay mechanics or rather narrative structure, but games like Outer Wilds, Fez, Tunic, where the exploration and discovery of the game is the end goal of playing the game, not just getting to the game's end state.
I'm not sure if there's an accepted term for these games, but I've always thought of them as "archaeology" games. There's a bunch of stuff, both plot and gameplay, that is hidden (sometimes in plain sight), until you discover it and find out what meaning it carries.
The biggest challenge with an "owned wealth" tax is how do you actually measure it? It's easy if it's held in cash in a bank, but most billionaire's wealth is is land, property, and how do you measure the value of a Picasso stored in a vault if they can slip the valuator a grand to say it's worthless?
Closing offshore money transfer loopholes, heightened tax on luxury spending (100% VAT on private jets and yachts?), making fines income-based, and treating capital gains the same way as income, are all more achievable.
I'm totally on board with the sentiment though.