Auto-translated
So, I recently finished playing through the original Heroes. None of the Campaigns caused any difficulties, but some individual missions really annoyed me, such as:
"Conquest" as Agrael (where you have to defeat Gilraen) - it was difficult here because of the initially incorrect tactics. You absolutely CANNOT capture the southern elven city first!!!
"Cultist" as Rai-Lag (where you need to capture 7 castles) - it was probably difficult here because Rai-Lag never got the Spellcasting skill throughout the entire Campaign((( As a result: there is almost no army, you have to rely on magic, but you cast spells very rarely...
Also, it was a bit difficult in "Invasion" as Markel (where you need to capture Mythgard and then, it seems, Hicam) - I was lucky to escape the island, avoiding the enemy hero, and capture Hicam with a relatively small army at a fairly early stage.
I had no problems at all with the Castle Campaign - I even played through this Campaign twice. Once on "Warrior" with a build focused on Chaos and Machines, and another time on "Veteran" with a build focused on Light. No problems at all.
Oh, yes, there's another point. I always thought that the Elves were the strongest race, but in the final battle with Kha-Beleth, he crushed them like babies((( Either the hero was weak (level 28, if I'm not mistaken), or he didn't have enough Spellcasting, or the demon army was much stronger than the others... In short, I had to take the Ents from Faidaen and give them to Rai-Lag. As a result, after the final battle, the Elves still had a decent army left - more than 20 dragons, over a hundred archers, and slightly fewer druids. The Elves, on the other hand, had... 10 Ents left. 45 black dragons destroyed them(((
Of course, the Light Elf was developed 1.5 (or even 2) times better in all parameters due to the huge number of bonuses in his Campaign, but... it was much easier with Godric, who only reached level 21.