Suggestion: Import/export save data to a file
Currently, save data is limited to where you play the game:

- Playing on a different site won't share the same save, and it's not possible to move from one location to another, at least not without hacking through developer tools via console.
- If you clear your cookies and history regularly, chances are that your saves are going to be erased, and any progress you've made will have to be done again.
- There's no way to share your progress with others, which can be a fun aspect for completionists, or games with custom maps/characters.
- If you switch between PC and mobile, there's no way of keeping your scores or in-game progress between both of them.
- Games ran through `w4 run` command will share the same save data, which will inevitably cause corruption between different saves.

My suggestion is to have an option to import/export save data to a file, allowing players to share and use them however they like.
Not only this solves a large amount of limitations, it can also provide a lot more if used creatively:

- Save editors for both players and developers.
- If done correctly, save data can be used as an expansion pack, which can provide extra content for games.
- For games with level editors or character creators, players could create and share their levels and characters.
- Moving your progress between sequels or other games (ex: carrying your old inventory, or unlocking a secret character after beating another game as a form of easter egg).