I picked up Fields of Glory: Medieval and Fields of Glory: Kingdoms recently.
FOG:M is a turn-based battle simulator. It rests on the principle of breaking up and routing your opponent more than slaughtering them, and has European and Middle Eastern army lists running from about 1000 AD to 1450 AD. However, it appears to have gone a bit "Paradoxy". By which I mean you can pick up the base game for free, except it doesn't have much in it so you'll need to buy a zillion expansions. I'm also a little bit suspicious about the army lists, which feel rather quantity over quality. This is possibly not unreasonable as medieval armies were maybe a little more homogenous than the ancient world, but still feels underwhelming.
I have some concerns because looking at how some of the army lists work and how the battle mechanics work, some of those army lists look like they are doomed to lose: their armies have no meaningful way of countering some opponents.
So far, via the procedural battle generator, I have witnessed some of these failings in action. You may be aware of the famous use of longbows by the English, and that they usefully contributed to some major victories. In game, they are utter trash. Archery in FOG works by attempting to disrupt formations so that the melee troops have an advantage when the battle lines connect. All very reasonable, because that's how they did work - forget those notions of massed archery slaughtering everyone. Unfortunately, what happens is that you sleet the preverbial storm of arrows into the enemy, and almost never achieving the disruption result. This causes English armies a massive problem because half the army are archers who get rapidly trashed in melee: once the enemy melee troops arrive they effortless crush the longbowmen and swamp the remaining melee troops. They have two designed "Grand Battles" (Crecy and Agincourt) where they avoid this by giving the longbowmen defensive positions, but outside these individually-designed battles they just don't work at all.
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FOG:K is a bit like Crusader Kings 2 with less dynastic stuff, or perhaps Europa Universalis 1050-1250. You know the drill. It's turn-based, but orders are issued and carried out simultaneously. I could almost like it, except that pretty much every part of it works not quite as well as its better-funded Paradox equivalents. What really staggers me is the genuinely absurd building system. This is a travesty of literally hundreds and hundreds of different buildings to put in your regions, many effectively replicating functions, producing goods that are required to make/subsidise other buildings as part of a trade/bonus system that is eye-bogglingly overcomplicated. Oh, and you can't properly choose the buildings you want, either: it gives you a choice of 6, which you can expand to choose from about 30 by expending a form of influence ("Authority"). In principle, it's actually quite a nice idea: after all, medieval kings did not exercise tight control of their nations, but could get a few specific things (mostly castles, it seems) done by deliberate order. In terms of the game, it just feels like a mess.
Just to give an idea of the insane bloat here, they have separated out cattle, pigs, poultry, despite them being pretty much functionally identical producing food and livestock. I get separating sheep at least (because wool). Then there's what feels like pointless buildings: build a butcher, turn your livestock into gold, but really, this is not interesting. Build a giant field, no particular use, except you can get a level 2 cattle ranch. Why not just skip the field straight to the level 2 cattle ranch? I can build apiaries to get wax to supply candle factories and maybe those candles do something, but honestly I'd rather none of them existed because it's just tedious, fiddly trash.
I'd also like more constraints on development. I can fill some of the most desolate, inhospitable mountains at the arse-end of Europe with a plethora of farms which build up a massive population and churn out the finest wonders and art of Europe. Fuck you, Constantinople, Venice and Paris: you could only dream of the wealth, sophistication and glory of Ullapool and Stavanger. I'm aware that technically you can do this in Paradox titles too, but at least it's much harder.