Opinions and brief descriptions on the Rtk games i have played so far:
Rtk II
My first Rtk game and what spark of my interest in Romance of the Three Kingdoms. Overall i feel the game relied way too much upon brute force. Once you have a sizeable number of troops and good generals you basically win the game. Maximum troop size is limited at 10000. The view of the battlefield is a straight look down plan view. Attack modes are: normal, simultaneous, charge and personal combat. Not much strategic depth and tactics for the game but it still manage to catch my interest and attention at that time.
Rtk III
First debut for the isometric view of the battlefield. More units this time such as crossbow, strong crossbow and cavalry units. Size of castles are more realistic and easily displayed in the isometric view with Capital Cities like Luoyang and Xu Chang possessing a bigger castle compared to castles/cities in less important regions. Tactics introduced are the ambush and pitholes if the advisor is present in battle.
Rtk IV
The map of China is the most well done in part IV in the entire series of Rtk games. Topographical features like mountains, valleys, wide and narrow rivers can be easily seen. However the city combat leaves much to be desired. For an invasion to be successful, you need to win both in the field and the castle siege. Field battle is okay. It is the city battle that is a let down. Although catapults and battering rams can be used in the castle siege in order to help defeat the city defenders, the space that took place is far too limited. Instead of four sides of walls that surround the city you are presented with only one small stretch of wall section to conduct your battle. Is totally unrealistic. It is this factor that drag the game down a lot. Another disappointment is the graphics for the characters. Although the graphical map of China is very well done, there is little improvement for the character pictures from part III.
Rtk V (chinese)
The introduction of battle formations is a nice one in part V. Some battle formations offer advantage when fighting in the hills, others on plains or water. Some are better suited for defense while others for offense. The presence of forts and passes on the battlefield add an interesting touch since they may have some strategic value which you can take advantage of. Execution of orders and plans is a radical change from all the Rtk games whereby you are given a number of "Hearts" based on your status and territories instead of the availability of the number of officers you have. This is restrictive and unrealistic. The number of orders you can execute should be based on the number of officers you have to carry them out instead of the number of "Hearts" you have. Basically the number of "Hearts" you have equals to the number of task you can execute or carry out in every turn. ie. five hearts=ability to execute five task/actions. Maximum number of task you can do in a turn is ten. Perhaps Koei invented this "Hearts" system to cut down on micromanagement? Together with part VI, part V is fun to play even though traps such as pitholes are removed from the battle. I consider its music to be the best in the entire series of Rtk games.
Rtk VI (chinese)
Koei took another innovation with the field battle and adopted the isometric view of the battlefield again. A bit of real time elements were added. Turns in Rtk VI are counted in a few days instead of each turn is one turn for most other Rtk games. Once you end your turn you basically sit back and watch as your units as well as the computer's engage in each other in real time. Each turn last a few days so the orders you issued can no longer be changed immediately. This encourages more careful planning or else a wrong command issued cannot be reverted till the next turn arrives a few days later in which during this period your unit might have strayed too far off course.
Some lost of control can be experienced when your unit is thrown into confusion or the unit (result from the general's characterisitics) decides to act on it own. When these events occur you just watch the units disobey instructions or just remain there in confusion till your next turn arrives a few days later. Morale have also become a significant factor in battle. Morale plummets when units are thrown into confusion, under heavy attack, fire or other traps. Larger armies may not win. With a smaller army, you can still win if you can manage to get the enemies morale to drop to zero which is not too hard to achieve. The introduction of region specific troop types add a lot more feel to the game. As reflected in history the Wu Kingdom has a naval advantage, Wei cavalry and Shu mountain troops. Controlling regions with these region specific troops will give you some advantage when fighting on the ground they specialise in.
Another feel of history that can be felt is the possession of the Han Emperor. As with the saying goes "Using the Emperor's name, i can order the dukes and princes around the country" which was what Cao Cao did. So if you possess the Emperor, that's what you can do. The Emperor will bestow titles upon you if you can accomplish the Emperor's task or request. The importance of titles for your warlord cannot be understated. Without titles, you cannot appoint your own officers to higher ranks. Experience attributes also make their debut in VI. Only a general with more experience can be appointed to a higher rank which in turn enable your general to command more troops in battle. Thus the importance of titles and accomplishing the Emperor's task/request cannot be ignored.Having mentioned the experience attribute, a very small dose of role-playing elements is present since experience can only be increased by using your officers to do task in that area; military or domestic.
There are a few historical scenarios based on actual historical events lasting from a few months to a few years as well for a short game. It is a welcome addition i would say.
The latest of the Rtk games. Overall the music is pretty good though it suffers the same repetition which have plagued all Rtk games. Character portraits are the best in part VI. More improvements in strategy and tactics were made. Personal combat/duel among officers are no longer left to computer. Koei has given the player some control in personal combat with the introduction of a few strategy "templates". Mainly they are all out offense, personal safety at all cost, capturing of enemy general and another one in between. In addition to that there are a few more sub tactics which you can choose in order. Character weapon effects and cutscenes were modelled and shown for powerful generals.
Legend of Cao Cao (chinese)
Being centered on Cao Cao, you will lead Cao Cao and his men in all the battle engagements that took place historically; 40 battles in all. There is a bit of role playing element involved since Cao Cao and his men will increase in "level" with experience. Same increase goes for the weapons and armor which will enhance their lethality and armor plating.
Artifacts play a part too and they bestow their respective users added abilities. The game is entirely based on warfare with narrations and conversations driving the interesting storyline. Although the game is pretty linear, Koei has added the option of allowing the player to choose between two options to spice things up a bit. Options like whether to attack in full force or spilt the army into two, breaking through one of two passes.
The later missions (30+) are increasingly difficult and you may wonder if the battle is actually winnable given the overwhelming number of units the computer throw at you. It is also the missions where triggers can be discovered and taken advantage of if you know how to exploit this aspect of the computer AI. What i meant by triggers are like triggering off computer reinforcements when you reach a certain terrain on the battlefield. Thus if you can avoid or delay reaching that "triggering" terrain you can buy some time to strengthen your defenses.
Purists might be put off by this game as certain attacks like poison attack, change weather, draining the life points etc are magical attacks. Other than this downside and the ficticous ending (if you don't mind) the game is enjoyable with the interesting converations and narrations for the story plot as well as experiencing the victories and defeats Cao Cao had in his life.
Focusing entirely on the life of Cao Cao, the game begin by tracing the life of Cao Cao from the Yellow Scarves Rebellion. However the ending is ficticous whereby Cao Cao unify the whole of China by conquering Shu and then Wu. Koei cannot be blamed for this ficticious ending since all if not most players will be disappointed to spend time playing and in the end Cao Cao passed away historically without conquering Shu and Wu.
Romance of the Three Kingdoms - Internet (chinese)
The internet version of Romance of the Three Kingdoms. An online multiplayer game huh? However if you ponder upon how balanced the game will be you will probably agree with me. It is an interesting idea for an online version of Rtk but to me it is totally unfeasible.
The two main obstructions to this reality are time and play balancing. First of all as any Rtk game player will know, Rtk is a game that is time consuming. I doubt anyone is able to spend so much time online playing the game with other players unless it is a short scenario. It is difficult to implement multiplayer mode for a turn based game. Those who have played Heroes of Might and Magic III will understand the agony of waiting for the other/s to finish their turn/s. Implementing a time limit to execute their turns might irritate some. Imagine waiting for someone who is managing 20 cities......
Secondly the play balancing is way impossible to implement. Players will go for Cao Cao, Liu Bei, Yuan Shao, Sun Quan. Choosing to play as Kong Rong, Gongsun Zan, Wang Lang is as good as courting an early exit out of the game.
To me, an online version of Rtk is totally unfeasible. I wonder why Koei released it in the first place.
Before reading any further please take note that i have not played this game and what i am going to write are strictly comments from someone who has not touch this game.