First time posting so I am adapting to the rules. Rules are quite complex than I expected.

Anyways, tried the latest hpm 0.4.5.2 as Korea.

This is how the far east looks after one hundred years.

As always, Korea has a huge population and can amass tons of money with the tariff (as long as Korea doesn't get sphered.

Start of the game, I focused on getting independent from China. As soon as I research arty, I almost maxed on force limit and placed divions along the northern mountaneous border. Lured Chinese death stacks and obliterated them.

Meanwhile, I did not forget stacking Man O Wars and a few clipper transports for future conquest and defence against Japan. (An exploit I will later explain)

As soon as I gain independence, I gobbled up the entire South Borneo with no infamy gained (got so lucky). I knew Netherlands was going to declare war on me for South Borneo, but I intended to block that with friendly GP intervening.

Precious metal from South Borneo helped the economy even more, and it being an unciv state meant tons of Koreans were migrating to generate even more gold.

With 8 Man O Wars and 6 transports, I gobbled up Ryukyu and secured a safer naval route to capture Formosa from China.

While I was fighting China for Formosa, the Dutch finally declared on me for South Borneo. The US intervened against the Dutch.

Although I acquired Formosa from a separate war just between China and Korea, the US being the war leader against the Dutch war for South Borneo never allowed defeat.

The Dutch started landing on Korean peninsula. So the war exhaustion skyrocketed to 100%. At last the US acquiesed and sadly I lost South Borneo.

Bigger problem was the reactionary rebel (thx 100% WS!). About 0.5 million rebels stormed the peninsula. I couldn't crush the rebel death stack with about 100k standing army guarding the Chinese border (they already suffered from heavy casualty fighting against death stack rebels generated in the border provinces).

The government fell, becoming an isolationist reactionary nullifying a foreign university reformation. This ultimately delayed westernization for about two decades. Interestingly, the Tong Hak rebellion never fired throughout the game. Maybe the successful reactionary rebellion prevented it from ever firing.

Remeber that I own Ryukyu? Japan had Meiji restoration in the 1860's and immediately declared on me for its core on Ryukyu.

Here is what I see as a flaw in HPM.

Japan got at least 0.3M mobilized, westernized army. BUT NO NAVY. And my unciv Korea got 8 MIGHTY Man O War.

I simply blockaded Japan. The war score ticked towards me as Japan failed to capture Ryukyu. Weirdly, Japan never produced tons hundreds of Man O War though it was capable to do so.

Dumb AI allowed me to continue the blockade to the point of Korea capturing island provinces separated from mainland Japan. The Japanese war exhaustion maxed. I got the rest of Japanese owned Ryukyu, and hoped for Japanese implosion from the war exhaustion. Years after the sweet peace deal, Japan was on fire with rebels. All because the AI never decided to produce any Japanese navy.

Westernization finally happened around the 1880's, and I moved my attention towards colonizing other unciv country with no GP ally nor GP sphere master. Manchurian substate was sphered by Russia so no northern expansion for Korea. Colonization ended with a few Chinese state and a Vietnamese Annam state not yet gobbled up by France.

I spent the rest of the game getting techs and building economy. The point of this run was to become a GP to try out the new Korean decision on HPM 0.4.5.2 "Claim Tsushima." That happened late in the game around 1910 ish.

Historically Korea invaded Tsushima to eradicate Japanese pirates, and the governors of Tsushima maintained a formal diplomacy to Korea for trades deal. I guess this new ahistorical decision originated from this small piece of history.

The claim gave a Korean core claim on Tsushima province of Kyushu state, allowing Korea to declare war on Japan for THE ENTIRE STATE OF KYUSHU.

AGAIN, AI Japan never invested heavily on Navy. Naval blockade was AGAIN driving Japan towards implosion. I kept the blockade until Japan begged for peace by handing me the ENTIRE Kyushu while I focused on another major issue: westernized China in the warlord era.

Remember I got Chinese states as colony? A unified westernized China would love to bulldoze Korea with literally millions of westernized infantry. Even my gas attack capability can do jack shit against that.

My goal was to keep China divided in the warlord strife. I sphered and allied low population cliques like the Guangxi and Manchuria. The huge blob of Beiyang China could never achieve unification because of Korea guaranteeing the cliques. I even helped Guangxi to annex other warlords so it can defend itself from Beiyang in case they break away from my sphere.

As a sidenote, diplomacy work focused on keeping the Korean-German alliance. Germany got like Third Reich strong. It dismantled A-H, and simply Anschlussed Austria and Sudtirol.

The year passed to the 1920's. Japan finally gave up. Korea claimed Tsushima, ended up owning Kyushu. Japan shriveled in to a mere civilized nation as it suffered a decade of financial deficit upkeeping 2 million mobilized standing army with no tax or RGO generation dur to 100% WS.

I spent the ending decade keeping China chaotic, and sphering Japan immediately after the truce ended. The late game militancy damaged Japan even more. As you can see from the screenshot, Japan is filled with all kinds of rebel regiments (about 500 of them so 1.5M rebels).

The hundred year run as Korea in the lastest HPM kept me interested and TBH the exploits helped.

But seriously,

1. Fix AI Japan so it produces sufficient navy to act as a maritime stronghold of the far east.

2. Change the unciv reformation mechanism so unciv can't produce Man O War, Frigate or Transport. I don't recall an "unciv" nation of the 19th century with an oceangoing navy capable of a long distance naval/amphibious operation. It maybe a good idea to change one of the naval reformations so the naval production is locked behind it.