These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Total War
Angst? What Angst?: If you massacre 3/4ths of a city when capturing it, the city will be happier than if you'd just occupied it. It's not crowded anymore, and that is one of the main sources of unhappiness. The fact that you've almost murdered everyone doesn't have any effect on the survivors' mood.
Essentially, this becomes the de facto occupation strategy in Rome; city grows to a particular population size and becomes unruly. Evacuate the current garrison, and let them revolt. Besiege the city with the garrison, and massacre the population. Rinse and repeat as necessary.
Though, this may be more of a case of these citizens being too busy shitting their pants and hiding from this occupation/mass execution force to make trouble, lest they be the next to come under fire.
Averted post-Empire, where looting a city results in massive happiness penalties that could easily spark a revolt within a couple of turns unless you cut taxes and fill the city with garrison troops. Looting usually works best when you don't intend to hold the city at all - just keep the (huge amounts of) cash and give it back or let the enemy retake it.
Geisha Assassins that have turned rogue in Shogun. The AI for Ronin/Peasants makes them rampage through nearby targets, they'll just start slaughtering the general and the replacements for the nearest enemy army, if it moves, then they continue on to the next target.
Moving back in time, or forward in terms of games, Horse Archers in Rome count too. In Medieval II, they've largely been nerfed to the level of Goddamn Bats as your knights can generally beat them; their true threat is to infantry armies or armies weak in cavalry. Horse archers in Rome can be countered by archers or cavalry, or by really heavy infantry who can soak up the missiles, so they're not that dangerous... unless you're unfortunate enough to deploy mainly phalanxes.
The entire Mongol faction, the Mongols in the first game in particular. Medieval II's Mongol horde was manageable if you had the right units in your army (lots of light and heavy cavalry.) In the first game, the Mongols got dropped in Khwarezm with about 10,000 men, far more soldiers than any one faction is liable to possess by that time. They made the Russian High Era start the hardest faction in the game. Don't get us wrong though; the Mongols of II are not to be messed with... and that applies to the ones who turn up in Shogun I too...
While we're striding on to Medieval II... Inquisitors. If you don't want these jerks killing your entire royal family and all your diplomats and merchants, you'd better have plenty of assassins on hand, because that's the only way to deal with them (other than putting them in a glass then stepping on them). For that matter, the whole damn Catholic Church is a Demonic Spider (no pun). The Papal favor rates are entirely random to start with, and are almost entirely random throughout the game, as you can LOSE favor for not building enough churches, or even while building plenty of churches. It can get to a point where you can be struggling merely to exist, and the Pope will FORCE you to devote your glorious faction leader to a pointless Crusade of Buttfuck, Nowhere or else be excommunicated. Even worse is when another Catholic faction decides it wants your land, attacks you, you attack it back, manage to retake your land, then while you're besieging your old capital, the Pope tells you to STOP FIGHTING WITH SAID FACTION and that if you attack them again within 10 turns, you will be EXCOMMUNICATED! Even just taking back your old capital will get you punished, and in the end THEY will get off with HUGE Papal favor... of course, if you know how to take advantage of the Papcy's crazy mindset, you can actually turn the tables right back on the other Catholic nations. Sure, the Pope will order you to hold off on attacking your enemies, but he won't bat an eye at you maneuvering an army into their territory and parking it right outside their city, and attacking the moment the enforced truce ends. The real trick to beating most Catholic nations is to launch coordinated assaults on multiple cities at once, or if you're man enough, just power through the excommunication. It's only a 20% penalty to public order, anyway....
Ensemble Darkhorse: Sweden in Empire gets a lot of Let's Play requests and fansite discussion, considering that historically, they are rather obscure.
Evil Is Cool: Several factions with the right motifs can seem like this.
Goddamned Bats: Though he's not (usually) an enemy to the Catholic nations, the Pope is nothing short of incredibly annoying. You get right in the middle of destroying your hated (and usually campaign-specific) enemy, and he demands you stop the war for five to seven turns. You don't, enjoy your excommunication. Not to mention he'll essentially force you to build a Crusade army and sometimes demand your faction leader take command of it. And he'll also send Inquisitors to your lands.
Though you can take advantage of the Pope's annoying tendencies by hitting a Catholic nation and triggering a "truce." Immediately afterward, during the "lull" in the war, you can move units into enemy territory, right next to their cities, without being molested by the enemy, who will be excommunicated if they attack you. Then, the moment the enforced truce ends, you can hit them with a coordinated assault, taking multiple cities. Next turn, the Pope calls for another truce. Rinse and repeat.
If you take control of Italy and have a decent number of cardinals, it's possible to rig the Papal elections. Assault Rome, kill the Pope, and elect your Preferati into the Papacy. Wham. Instant reconciliation, perfect relations with the Papal States, and you can order up Crusades on demand. And if your elected Pope becomes troublesome (like, say, demanding Rome back) and excommunicates you, an experienced assassin can put him in his place.
Nightmare Fuel: The Geisha in the first Shogun. Even when they are on your side, it's hard to escape the fact that these are inhuman white-faced super-assassins you're dealing. Their most routine targets, the generals, happen to be their most terrifying kill- they begin by playing music on a lute for the general and his guests, camera cuts away and we here a ruckus coming from the room, the Geisha walks out and we cut back to the room- the general, and his pals, bloody, dead, and hanging from the ceiling by the lutes wires.
The opening of Napoleon can be a mild instance of Nightmare Fuel for some. Napoleon's speaking, delivering his Badass Boast, and then... he's on an unidentified shore, ships burning in the background, and one huge battleship lying on its side on the beach. He gives the order to burn it. It's the HMS Victory, Nelson's flagship. For Nelson/England/Royal Navy fans... the sight is chilling.
The Scrappy: The advisers, who pop up ever time you click most things.
Scrappy Mechanic: Surprisingly enough for a series this long, there really aren't that many. There is one that mars what is otherwise a brilliant game, Shogun 2. "Realm Divide" basically has Japan ally up and split into two sides when you reach about 15 provinces or so (Out of about 65). These sides consist of you and whatever allies you have (until they inevitably backstab you), and the other side consists of everyone else in Japan. If you don't think that's unfair enough... each clan arrayed against you is given multiple gigantic stacks of veteran units every turn.
This is also prevalent in Rome and Medieval 2; once your empire is large enough, the other factions will gang up on you, often while still remaining at war with one another (yet not doing anything about it). Empire generally fixed these issues, as long as the player was careful not to upset the other factions.
Total War Rome II fixes this slightly. Rather then every single faction ganging up on you, only the other factions within your subset(Roman, Greek, Ptolemaic etc) gang up on you.
Spiritual Licensee: Given the scales, time periods and battles involved, the Total War games tend to be reminiscent of various movies. More specifically, you've got Rome, which is reminiscent of Gladiator, and the Shogun 2 DLC Fall of the Samurai, can pretty much pass itself off as a prequel to The Last Samurai. Indeed, at least one reviewer has called it the "Tom Cruise DLC."