It's just occurred to me to mention Marcus Rowland's excellent Victorian role-playing game
Forgotten Futures, which he's been successfully selling as shareware for years. Each collection comes with one or more Victorian SF or fantasy novels (in html format) together with the rulebook, a worldbook based on the novels, and a book of adventures. As with Richard Herley's novels, you can download them for free, and only pay for them if you like them. There are nine different games in the series, and they're usually nicely illustrated with period illustrations too. There's also a PDF version of the main rulebook.