Technology is a gameplay mechanic in Empire: Total War, Napoleon: Total War, and Fall of the Samurai.
Empire: Total War[]
This tech tree is that of Great Britain. No other nation has access to the Screw Breech, located at the bottom left corner.
Introduced in Empire: Total War, technology can be researched by factions to improve their economy, National Prestige, and military capabilities. Technologies may be researched at schools, and can be sped up by having gentlemen at schools and building down the right path for cultural buildings in major cities.
Technology is separated into three areas: Military Technologies, Industrial Technologies, and Enlightenment Technologies. Military technologies improve the military aspects of a nation's army by upgrading equipment, unlocking more advanced troops, increasing their movement range, and reducing their training and upkeep costs. Industrial Technologies increase the profitability of industrial buildings, the population impact of farms, and unlocks new industrial buildings. Enlightenment Technologies increase the town wealth of regions and increase the profitability of trade while unlocking better buildings related to trade, but also increase public unrest in regions with schools as people become better-educated.
As schools have no purpose after all desired technology is researched, it is best to destroy them and replace them with cultural or economic buildings. Not only does this help with population happiness or the production of wealth, it helps reduce clamour for reform which schools foster.
Research[]
Every technology in Empire: Total War requires a certain amount of turns to be fully researched. This, in turn, is decided by the amount of research points the technology requires relative to the amount of research points provided by the school and the gentlemen conducting the research. For example, an un-upgraded School offers 9 points of research per turn. If a technology requires 50 points, then the school would need six turns to complete the research. If a Gentleman is placed inside the school and gives 6 points of research, then the research would instead be completed in four turns.
In addition to providing their listed benefits, research certain technologies is a requirement for moving down the technology tree.
Napoleon: Total War[]
Technology returns in Napoleon: Total War, and functions in a very similar way, albeit with different tech trees. Technology is now split into civil, military, and industry trees.
The Peninsular Campaign[]
Technology returns in The Peninsular Campaign, again with separate tech trees. All factions have different technology trees.
Total War: Shogun 2[]
In Total War: Shogun 2, arts replace technologies, but function in similar ways. Instead of allowing multiple schools to research multiple different technologies simultaneously, only one art may be mastered at a time. While certain agents and buildings increase the rate at which technologies are researched, it takes hundreds of turns to research every art, so prioritizing more useful arts can be key to achieving victory.
Fall of the Samurai[]
In Fall of the Samurai, technologies replace arts, but function similarly to arts in Shogun 2. There are no longer buildings or agents that increase the rate at which technologies are researched, but to compensate for it most technologies are researched much more quickly.
Technology trees are unlocked through increasing modernisation. Modernising increases the rate at which technologies are researched.