https://www.warzone.com/SinglePlayer/Level?ID=1079664
I think the map where you got 500 troops vs 100 is crazy. No way you can win that unless the computer mess up. I guess there is some loophole you can find that make the computer make stupid moves all the time and not attack you, but don't feel it is based on any kind of actual strategy apart from using the abandon card at the right time when the enemy attack you from many fronts .
Lot's of players think this map is impossible, or luck based. It is doable, and actually requires little luck. It might seem strange but you need way more strategy than luck!
https://www.warzone.com/SinglePlayer/Level?ID=1091957
Ceasars challenge is good. I got more than half the map although then they used some sanction card which fucked me up cause I had focused on gaining income. Why did you add that just to them? Feels like it make it insanly hard then since it feels impossible to match the income of the computer when you need 2/3 of the map to equal them. I guess the key would be to kill the partha general and use your early income to build up a big army for that job while being able to get the boss to move after you. Still though it would make it very hard to defend with low income and maybe you just need to try to make partha get most of the troops so when you kill the commander they turn into neutrals. After I got Italy the boss started to move against me as well and I just couldn't win the battles while also dealing with the bonuses being broken.
The sanction card was added with the purpose of keeping the game interesting after the first 15 turns, in which you could easily expand. The challenge is to finish off the Parthian commander while under attack from all directions. It's not possible to defend everything, but reaching the commander shouldn't be too hard!
https://www.warzone.com/SinglePlayer/Level?ID=1090435
The unite Japan challenge is also fun. I think the same key then is to kill the commanders at the right time. A bit annoying if the commanders move in poor directions from the start. Then try to get huge neutral stacks when you do it in strategic areas. I killed the 2 early commanders a bit too fast since I thought that would help, but after that I couldn't expand anywhere and the enemy got more troops making it harder to chase down any more commanders.
Tried Unite Japan again. Got the first 3 commanders down and almost the 4th although the al with massive armies from sea destroyed my protection so I lost the key bonus I needed to progress. You got to hope the al are stupid enough to try to run after your troops in the direction you want. If not then they can often destroy you. Also the commanders often run away, but it is very difficult to force them to move in other directions since you can normally only attack from one direction while the generals run the other way. Advancement in sea is impossible unless you can lure the troops into the mainland and if you do it will be difficult to keep enough bonus up.
I feel getting Kyoto early could be key since you can lure in enemy troops into the City which will slow them down. Ideally you would like to trap a lot of enemy troops inside once the commander is down. Will try this again I think, but not sure how much progress I will make. Something that worked with good luck might not do it with bad luck.
Unite Japan is a scenario that is pretty open to how you wanna play it out. Sometimes you have to blockade, sometimes you gotta let the enemy stack up the troops, sometimes you have to run and sometimes you have to go for the blitz attack on the enemy commander. I think this level is pretty well rounded as it requires luck, skill, vision, ai knowledge, and a bit of everything that a good sp should know! It is hard, but with a solid strategy you should be able to get a win most of the time (50%+ of the attempts)