Unicorn Overlord was almost my goty 2024, only barely beat out by Shadow of the Erdtree. Looks like I put it at #6 on my list. Looking again, that still seems right to me; this game got its shithooks in DEEP and I mainlined it hard over a very short span of time (for about 80 hours' play clock in the end).
At its core the most engaging thing about it is the army-building and customizing. There are so many different character classes and all of them are powerful and useful in more or less equal measure, even if only in a certain niche (but then, are very useful in said niche), and all in a wide variety of different ways. I was impressed with the breadth of character and class design they brought to the table. You build units out of 3-5 characters, and each one is like putting together a whole RPG party in and of itself (usually with roles like tank, damage, support, but very flexible to let you get crazy if you want), and by the end you get up to 10 of those units. You can play around with specializing or generalizing your units, with different forms of offense and defense, status effects (powerful and reliable, unlike in most games), and combos thereof. You can granularly program each individual member of each party not only on prioritizing conditions like "use your row attack if there are 2 or more enemies in a row" and "use your anti-cavalry attack if there's cavalry in the front row," and the options they grant you are a damn near, if not quite entirely, perfect list of tactical elements you want/need (want to only activate a certain attack if the enemy has a certain debuff, but only if they don't have the chance to use a more powerful attack on a large group?). Also some characters have abilities that can trigger off of other actions, so you can e.g. set up your caster to buff the party at a certain time to trigger a powerful healing reaction from your healer, or any of a number of very intricate and detailed possibilities. Then there's all the equipment you can find and set your characters up with, some of which even give them extra abilities...
Then you take all those units of characters on the road and deploy them in battle. When they actually encounter an enemy unit, they do combat automatically, but in the meantime you're guiding them around the map. The ultimate objective is to capture a certain enemy stronghold, typically, but along the way you'll need to capture other towns or forts, disable dangerous ranged support from towers, beat up fortifications, send someone out of the way to trigger a strong environmental effect, send a fast party into the range of heavy artillery to take it out before it rains destruction on you (and then use it against the enemies yourself)... Different character types in a unit's leadership can make a unit mounted (fast) or flying (versatile), so you can be executing multi-pronged strategies - two units to defend the west flank, a flying unit to go over the east mountains and capture the fort sending reinforcements, while your cavalry rides the main roads against the enemy and takes the towns along the way. Maybe when one cavalry unit reaches a midpoint town you swap it out for a beastfolk unit to take advantage of the buff they get at nighttime.
But ultimately, it's about building an intricate machine, then winding it up and watching it work. If you like the part of RPGs about strategically building parties from characters with distinct strengths and weaknesses, you'll love this one.
Not every battle is as big as the above (made-up) example; some are relatively small, or just not as complex. I do wish there were more of the large battles with multiple fronts and objectives.
It's got a nice big world map with distinct zones, gathering materials, hidden items, a hot-and-cold mining minigame with secret treasure map rewards, legendary weapons...
The art is absolutely beautiful, because Vanillaware, albeit in a more...normal way than their usual games. It's a little less exaggerated, less ethereal, more grounded than Vanillaware's typical house style. That's good, as it lacks some of their usual...excesses, we'll say (it's their least horny game by a country mile), but also makes it a bit less striking and distinctive. Still beautiful, though! Music's good too—nothing particularly memorable, but good at its job.
The story is the weakest point. It's not bad, but it's a very simple, very straightforward, basic-ass Fire Emblem story built out of cliches and common tropes. The characters are pretty generic as well. This one is definitely about the mechanics first and foremost (and luckily the mechanics are extremely good.) The other issue is that it's pretty easy. I breezed through it on normal difficulty with nary a hiccup, but that might just be because I engaged very hard with the army-building and they were giving some latitude to more casual approaches? Psh, pfft. Piffle and hogwash, I say. They do have harder difficulty settings that impose some different mechanical limits in addition to just giving you less good number and more bad number (e.g. imposing a limit on how many items you can use during a battle, adding a new element of strategic consideration where there wasn't one before). And like I said, there aren't as many battles that really explore the limits of the system and test your capabilities. Also, despite feeling like a perfect candidate for a New Game+ mode, there isn't one! Fuckin' c'mon!
In conclusion, Berengaria is best girl and my wife. Literally! You get to pick someone for your main character to marry, based on affinity ranks in the FE tradition. (Oh, that reminds me, UO is also cowardly about the possibilities of gay romance, so choosing to "marry" another man usually results in an FE-like Best Bro situation. Some characters hint somewhat obliquely at romance, but it's left vague at best. Even the het romances are a bit undercooked; only one of the four options I tried out before making my final decision actually had a kiss animation at all, the others just kinda stood closer to each other and blushed a bit. But they're still overtly romantic, compared to pussyfooting around the gay options.)
Anyway. Unicorn overlord good. play it
OH AND the demo is very generous, it's just "here's the full feature-complete game with a 7-hour timer, go nuts until the clock runs out" so there's no reason not to try it out!