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As I have read but not played with the system, please take this with a grain of salt. If anyone with experience with the system in play differs with me, I defer to them.
The original M&M zine isn’t very indicative of the revised version presently available, so it may give the wrong impression of the system as it stands.
M&M is not a BW sequel. While it is still a character driven RPG, it doesn’t share mechanics with BW or TB
M&M is kind of OSR, in the sense that it is derived from Basic D&D, but has a large number changes from the baseline D&D expectations in setting, mechanics, and narrative style.
M&M uses all the standard polyhedral dice. d20s are used for much of combat and save resolution. Skills typically use d6s but can move to d8, d10, d12, or d20 depending on expertise or modifiers. d100 may be rarely used. d4s, d3s, and d2s will be used for some weapons (physical or verbal) or hit points. All of these may be used in the character creation process, which utilizes a class/lifepath system.
The setting is a slightly fantastic historical France. Miracles or magic may be worked and alchemical formulas may produce unbelievable results, but those things are rare and incredibly hard to master without dedication. Even a starting “magical” character may be unable to successfully invoke the spells or rituals they have discovered. There are no monsters in the sense of owlbears or mimics. Supernatural beings like angels and demons may be implored for aid by the wise or foolhardy, but they do not have game statistics to overcome.
The revised version of the game is not built around dungeon crawling. While there are rules for tactical combat, there’s also duels of wits (including attacking enemies in the press), social standing, obligations and wealth. You can certainly run into a dungeon or crypt to uncover some nefarious plot and win out with force but it’s much more grounded in historical fiction than your typical “you all meet in a tavern”.
It depends on what you want out of the piracy. Smuggling and navigating are certainly supported as is some swashbuckling combat, but ships aren’t fleshed out to the extent that, say, horses are.
Politics are heavily baked into the setting. Characters even have “Mentalities”, which are scores to show how much they know or how strongly they feel about their religion, country, and politics. How much they are able to move the wheels of history depends on the campaign, but there is a ton of historical setting information to give context to the characters and drive stories.
Large scale wars are detailed in historical information, but there aren’t mechanics for fielding armies against one another in battle.
For tone, I’ll quote the “More Miseries” volume here:
we hope that you will strike a tone[…] focusing on the action and values of complicated protagonists as they attempt to fight the tide of history with wit, strength and courage
In addition to the historical setting information and plot-hook ready character creation, the “More Miseries” volume spends about a third of its pages laying out how to sketch a plot, run sessions, weave in historical events, and involve character beats.
If the table is willing to explore M&M as something different from D&D 5E, they may well enjoy it. If they are looking to explore the same kinds of gameplay and story as they get in that system, it is unlikely to be a good fit. In particular, the character creation heavily uses randomization to generate background (including their political leanings and expected lifespan) which some players will bristle at if they’re looking to make a specific kind of character; if they’re willing to let the whims of fate lead them in unexpected direction though it can be incredibly satisfying.
The Books 1 & 2 bundle has everything you need to get a feel for the system and start playing. Book 1 has rules for the game system, and Book 2 contains information for making characters. Book 3 layers in the mystical and magical elements, so those are easy to leave out if desired.