Kessen 2 and 3 were more fictional anyway, I think they should keep that up. Tactics, Ro3k, Dynasty Warriors, ETC all bring different play styles.
But I think I liked two the most, and that is added by....:
1. Though the voice acting was bad (2001, so whatever) they did bring some unique people. (Cheng Yu, Pang Tong, Himiko) And, besides how a few officers were a bit off..(Yu Jin, Yue Jin, Li Dian, Guo Jia, Guan Ping, Zhang Ren, Wu Yi...so on) It was fun to see what each person could do.
2. No battle was the same, and they were always fun.
3. The special abilities had a long list, and always fun to use.
4. Despite the whole Liu Bei and Diao Chan thing, it was fun to see how Liu Bei and Cao Cao changed.
5. How all forces had a large amount of forces.
Now, why am I talking about Kessen two only? This is what Kessen 4 should be:
1. Ro3k style, close to Kessen 2. I know a lot of people like the Oda time period, but Keoi does better with Ro3k, the story can be pushed further in my opinion, and far more intresting people could be made.
2. More officers, more fights, but same style of fighting.
3. Some control of minor officers (Think Zhou Cang or Dian Wei) Could betray or be captured.
4. Other officers (Liu Zhang, Zhang Ren, Wu Yi, King Mulu, Meng Huo, King Duosi, Wu Tugu) should be able to be included.
5. Better voice acting.
6. Removal of Diao Chan unless Lu Bu would be added. Maybe as the first boss of the game for Cao Cao and Liu Bei (like two battles max, maybe together)
7. Changing Xiahou Dun, Yuan, Yu Jin, Yue Jin, and many others.
8. Adding Yuan Shao for a Guan Du battle for Cao Cao.
9. Adding the battle for southern Jing for Liu Bei.
10. Changing Sun Li's placement. Make her the lover of Liu Bei (I know, but its better then Diao Chan) This is so Wu would have more to do in this storyline, and making them a third playable kingdom.
11. Adding MANY officers to Wu.
12. Changing the sea battles a little.
13. If wanted, make it so every force is playable for a least one fight. (Have it be unlockable for beating a mode) Like, unlocking YTR, Hu Lao, Guan Du for Shao's side, Cheng Du for Zhang, Tong Gate for Han Sui / Ma Chao, Gongsun Zan side and Yuan Shao side for a northern fights, and a Nanman fight.
14. More unit types.
15. Lastly... more duels!
Spear vs Elephant
Sword vs Elephant
Sword vs Magic
Magic vs Magic
Elephant vs Magic
Elephant vs Magic
Magic vs Spear
Spear vs Elephant.
And having special duels (Liao and Yu) be different.