Cavaliers of Mars is a game of cooperative story-telling in the swashbuckling, high romance, high adventure setting of Dying Mars. It is not a traditional TTRPG; it does make an interesting sourcebook for TTRPGs.
The game consists of rolelplaying adventurers in order to accumulate Drama Points, which are used to either benefit a character or make alterations to the story. The GM has final discretion on all uses of Drama Points. When it works, players and the GM are effectively co-writing a story in real time, livened up with dice and strategic swashbuckling action. When it doesn't, players are combatting the GM to give advantages to their characters, while the GM feels obliged to shut down players' unbalanced input.
Example In SWADE, the GM might tell a player that they recognize a figure from their past in the crowd; in Cavaliers, the Player tells the GM that they recognizes a figure from their past in the crowd, and then the GM plays the figure. A story unfolds, directed by the GM but shaped and told by all involved.
As for the setting, it is delightful and draws heavily from the sci-fi romances of the mid 20th century. Flying ships, ghosts driven on the wind, duels at night beneath rainbow-colored lanterns, mysterious lost cities, mad cults...
One thing I disliked about Cavaliers is the demand that the GM be a writer, rather than a GM. What are the dangers of canal travel? Unknown. How much technology is actually understood? Not defined. What the heck is a "shipsling"? You'll never know - or rather, that's entirely up to you, and your story. Total creative freedom is probably appropriate for a cooperative writing game.
Addendum: complaints about the complexity of the rules are unfounded. This is a game about shared imagination and dramatic scenes. Action is cinematic, not strictly bound by hard rules - explain what exciting stunt the character does, realize there was a failure and make that exciting too. If someone is poring through the rules to gain advantage for their character... well, that person won't be a good Cavaliers player.
[4 of 5 Stars!]