I still think Caminus Aureus shouldn't give Mithril
Anyway, I had some more ideas about the mechanos:
A new damage type, Power; it would have a chance to cause a Shocked promotion on units, making them unable to heal and lose 2

points.
Some Mechanos units would start with Power damage but mainly, it would be tied to a 'mithril replacement', needing a building to auto-apply a +2 Power damage prom to units built in the city, NOT replacing Iron Weapons;
(but no access to Mithril, as it's more magical than other metals)
I would also like it if there was a Train unit (national limit: 4) with 4 moves, 6 cargo and which would require railroad to move and Iron to be built. Would be necessary to teach the AI how to use it though.
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Also, ideas for a reworked affinity system: instead of just increasing strength, make it so affinity can give promotions; say, set it so promotion X needs a affinity to fire to 1 so be gained. 'Affinity to fire' would need another promo to be activated on the unit, or may be part of it. So you'd see something like Chalid, 2 fire affinity; it won't mean he will gain 2 strength for each fire mana you own. Instead, it will mean his affinity to fire will go up by 2 points for each fire mana you own; and the total of points will determine what 'affinity-promo' the unit will gain
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Had an idea about reworking the technology trading system...
Currently, once you know one certain tech, you can trade techs with other people (ie, with Writing). What I would like to is to set it so you'd need some specific techs before trading some others. For example, Education would allow trading of Arcane Lore... while Writing would only allow you to trade, say, KotE.
But the main idea would be to set a 'leak ratio' so that if you are in contact with another civ which know a certain tech, you will progressively gain beakers towards it even without researching it. This ratio would depend on the tech but also on how you interact with said civ. The more trade routes, the stronger the ratio; but war won't let you gain anything. Spying might also become handy to get techs...
(One idea could be to then remove tech trading completely)
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An idea linked to this would be to make Steam Power leak. It would like very slowly so that a non-Mechanos civ would pop it only during Renaissance or so.
I know, this may sound wrong as it is Mechanos' unique tech and that FFH has a tradition of preserving uniqueness as much as possible. But my idea here is to allow the FFH world to transition to a steampunk technology through the Renaissance, gaining access to trains, zeppelins and such in late game, a way to, maybe, spice things up.
Mechanos would still be unique enough because they would have it since a long time already and the other civs wouldn't have all the unique things of the Mechanos (like, no refined mana).
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And that's it for idea time!