Slitherine

I bought this DLC for a 61% off discount. I played through the campaign on max difficulty level (Kamikaze difficulty). My verdict: Morning Sun features many unhistorical elements and has many bugs, yet it is fun. The discounted game is worth the money.
I have reported all the bugs I found in the OOB bug submissions sub-forum on the Slitherine forum.
Now, I will introduce each of the 11 scenarios from first to last, and put forward my criticism.
Beiping-Tianjin (1937.7.15-28):
This scenario is about the Imperial Japanese Army (IJA) defending its China Garrison Army (CGA) garrisons against piecemeal Chinese attacks. This is unhistorical, as the only Chinese offensive in the real-life battle occurred on July 29th in Tianjin. It targeted the Japanese concession in Tianjin.
Apart from defending this concession, which is historical, the CGA defends northeastern Beiping and a railway bridge between Tianjin and Langfang, which is unhistorical. The CGA in Beiping should be garrisoned in the Japanese barracks of the Beiping Legation Quarter, southeast of the center of Beiping, and in Fengtai, south of Beiping.
At the beginning of the scenario, Japanese troops are to rush to the front line and protect their CGA garrisons, preventing their annihilation. Then they are to counterattack and occupy all primary victory points to win the scenario.
The Chinese air force appears in the middle of the scenario, which is also unhistorical. Historically, the Chinese air force debuted at the Second Battle of Shanghai. Another unhistorical element is the Chinese Renault FT-17 tanks appearing in the scenario. There were no such tanks in the real-life battle.
Operation Chahar (1937.8.5-9.9):
In this scenario, the Japanese aim is to secure the Beiping-Zhangjiakou railroad and pacify Chahar.
The Chinese air force makes an unhistoric appearance. The 75 mm Bofors M1929 AA gun, a weapon used only for the defense of the skies of Nanjing during Operation Chahar, also makes an unhistoric appearance.
Shanghai (1937.9.14-10.29):
In this scenario, Japanese Marines '37 and Type 94 37 mm AT guns will become available for purchase. A5M2 fighters will become available for purchase on October 1st, 1937.
In this scenario, the Imperial Japanese Navy Special Navy Landing Force and the IJA are to occupy the whole of Shanghai City, its outskirts, and beyond. An IJA landing force will spawn in Hangzhou Bay once the Japanese capture 3 specific towns north of Shanghai City.
The scenario map could have been done better.
The map scale is too small for this scenario.
Important geographical features and historical battle sites are misrepresented or missing. Huangpu River, located east of Shanghai City, is 400 meters wide and 9 meters deep on average. Yet in the game, it is represented as a small river that ground units can cross at will. This river should be at least a hex wide. Suzhou Creek, a 50 m wide river that separates the International Settlement and northern Shanghai City, is not on the map. So is Wusong Creek (now called Wenzaobang), a 100 m wide river north of Dachang, which the Chinese used to hold back ferocious Japanese assaults for two weeks.
Another result of the small map scale is the underrepresentation of the scale of the battle and Chinese tenacity. The second battle for Shanghai was the second-largest battle in the Sino-Japanese War, with a million soldiers involved. In history, from September 11th to October 20th, the IJA advanced only five kilometers. On the scenario map, such progress is equivalent to advancing less than two hexes' distance! Also, the scenario could be won within this time range. Thus, the game makes the battle shorter than it was in history. Besides, there are unnamed settlements and redundant lakes on the map.
There are also some historical inaccuracies. My capture of Luodian, a town nicknamed “Flesh Mill” because of the bloody fighting there historically, did not even induce a single Chinese counterattack. The Yangtze River Battery, a fortress located in the north of the map, did not exist in history. Wusong Fort, a fortress in this scenario, was destroyed in the first battle of Shanghai in 1932 and was not repaired. Thus, it should not be represented as a fortress in-game. In-game, the Chinese built bunkers and laid minefields along the coast. That did not happen in history. Meanwhile, the pillboxes defending Wuxian (now called Suzhou) that did exist in history are missing from the game. In real life, the landing at Jinshan happened on November 5th. However, by then the scenario had ended. The scenario should end on November 19th. In history, that is when the Japanese breached a belt of Chinese fortifications connecting Wuxian and Jiaxing known as the Wufu Line. The second battle of Shanghai ended with most Chinese defenders withdrawing from the region of Shanghai in a rout. Yet most Chinese were destroyed in this game scenario, indicating a lack of Chinese units.
In this scenario, there are misrepresentations of units and time-traveling units. The Pinghai, a Chinese 2500-ton CL, is represented as a CL Light Cruiser. However, the Izumo, a Japanese 9500 t armored cruiser, is also represented as a CL Light Cruiser. The Ying Swei, another Chinese 2500 t CL, is represented as a gunboat! The Pinghai and Ying Swei would be better represented as destroyers. Dinghai, a Chinese gunboat that should have sunk as a blockship in Qingdao, makes an appearance in the game. I have not found any evidence of the Japanese CA Myoko participating in the battle, yet it also appears. The Vultee V-11, a light bomber made available for the Chinese only since 1938, appears as well.
The developers seem to have forgotten to make the longer barrel version of the 15 cm SFH 18 a type of Chinese unit in Shanghai.
Xuzhou (1938.3.5-4.13):
In this scenario, Japanese Engineers '37, Type 98 20 mm AA guns, Ki-27 fighters, D2A bombers, Ki-30 bombers, and Ki-32 bombers become available for purchase. The Type 95 Ha-Go tank becomes available for purchase on April 1st.
In this scenario, the IJA has two armies converging on Xuzhou. One comes from the south, and the other from the northeast. In real life, there was a third army. It came from the North. It was this army that walked into the Chinese trap at Taierzhuang. This Japanese force sustained heavy casualties as a result and retreated. After the failure of their first attempt to take Xuzhou, the IJA sent its armies west and linked up west of Xuzhou, surrounding the city and many Chinese armies. Most of the Chinese managed to sneak through the Japanese encirclement and lived to fight for another day. However, this is not represented in the game.
There are more unhistorical elements to this scenario. Historically, no Chinese armor was deployed at the Battle of Xuzhou. Yet, I see an SdKfz 221 and a PzKw I. Historically, most Chinese armies in the Xuzhou region (Fifth War Zone) were poorly equipped. However, I met many Chinese Infantry '37 and Chinese Heavy Infantry '37, a match for the well-equipped IJA.
Lanfeng (1938.5.15-6.1):
In this scenario, Soko Sagyo Ki engineering vehicles and A5M4 fighters become available.
In this scenario, Chinese armored forces are going to counterattack an IJA vanguard. The IJA must rush reinforcements to stabilize the situation and ensure their vanguard's survival. Then they are to capture Kaifeng and Zhengzhou.
Historically, the Chinese surrounded a Japanese division of about 20,000 men with about 200,000 men. Most of the Chinese were infantry. After other Japanese divisions came to the rescue, they seized Kaifeng. To halt further Japanese advances, the Chinese blew up the Yellow River dikes, resulting in the flooding of a large area in front of the Japanese. Thus, the IJA was not able to take Zhengzhou.
However, in-game, the Yellow River disappears north of Lanfeng! This is horribly wrong. The Yellow River is the fifth-longest river on Earth, with an average width of 500 meters. It is not a river you can wade through. Ferries are needed to cross the river. The river should be a hex wide in the game.
Most of the rivers south of Lanfeng do not exist in real life. The irrigation canal west of Xinxiang should not exist because it was dug in the 1950s.
The village in the northeast corner of the map should be turned into an Asian town hex and named Dongming.
Wuhan (1938.6.12-9.18):
The player's army will advance along the Yangtze from Anqing to Wuhan. A second IJA army will converge on Wuhan from the north. This army is small. It will arrive when the player's army crosses a line on the map. Supply lines are said to need protection from communist partisans operating in the Dabie mountains. Yet, the partisans do not do any damage to the player's supply.
The Chinese air force spawns next to its airfields when IJA troops get close. That is unfair, as the player does not get an early warning of their presence through recon and cannot preemptively attack the aircraft hangars.
Nanchang (1939.3.15-4.23):
In this scenario, Japanese Infantry '39 and Ki-27 B fighters become available for purchase. Japanese Heavy Infantry '39 became available for purchase on April 11.
In this scenario, the IJA is required to divert units to protect its supply trucks traveling along the Yangtze River from National Revolutionary Army partisans. 5 air command points would be given when the IJA breaches the Xiushui river line of the Chinese. The IJA must capture Nanchang and defeat a Chinese counterattack, and then advance further south to win the scenario.
Changsha (1939.9.15-10.24):
In this scenario, Japanese Marines '39 and Type 97 Chi-Ha tanks become available for purchase.
The IJA approaches Changsha from four directions: north, north-northeast, northeast, and southeast. Historically, the northeastern force did not exist, while the southeastern force never reached its assembly area at Yichun due to fierce Chinese resistance. The Chinese stopped the north-northeastern force in the hills, while the northern force got close to the city but retreated due to a Chinese counterattack. The Japanese failed to take Changsha again in 1941 and 1942 and would only succeed in 1944.
Nanning (1939.11.15-12.9):
In this scenario, Type 90 75 mm artillery becomes available for purchase. Japanese Engineers '39 became available for purchase on November 17th.
The IJA conducts an amphibious landing near Beihai. The Japanese then are to advance inland to take Nanning, and then fight off a Chinese counterattack, and then destroy all the units guarding Kunlun Pass. In history, the Japanese landed between Qinzhou and Fangcheng. The Chinese counterattacked only after the IJA had captured Kunlun Pass and succeeded in retaking Kunlun Pass. Guangdong (1940.1.1-3.19):
Since this scenario, A4N1 fighters have become unavailable for purchase. Japanese Infantry '40 became available for purchase on January 7th. Japanese Heavy Infantry '40 became available for purchase on March 15th.
In this scenario, the Japanese defend the area they occupy in eastern and southern Guangdong province against Chinese attacks that come in waves. In history, it was the Japanese who attacked first. Their offensive began on November 27th, 1939. The Japanese then decided to withdraw half of their army to reinforce their forces in Guangxi province. On November 26th, 1939, the Chinese launched their counter-offensive. On January 1st, 1940, the Japanese started retreating. The Chinese stopped their offensive when they had taken back all the territory captured by the Japanese in November and December.
Chongqing (1940.8.25-9.18):
In this scenario, A6M2 Zero fighters, Ki-48 bombers, Ki-51 bombers, B5N2 Kanko bombers, and D3A Kanbaku bombers become available for purchase. Ki-32 bombers become unavailable for purchase.
In this scenario, after advancing westwards along the southern bank of the Yangtze River, the IJA attempted to cross the river and secure local airfields for continued air support before launching an assault on the Chinese wartime capital. This scenario is fictional. Japanese ground units never came close to Chongqing or capturing Chiang Kai-Shek. The Chongqing Fortress in-game is also fictional. There was only an AA battery at the real-life site of the fortress.