TL;DR Unless you're a masochist who likes starting over half way through try something else like Disco Elysium or Pathfinder. There was a lot to like and admire in Underrail attempting to recreate the ambience and playstyle of games of yore, but as with all such projects there comes a point where the choice to ignore changes (and lets face it improvements) in game design since the 90's crosses a line from reverent into pigheadedness. The highly detailed crafting and combat systems were extremely interesting and satisfying to explore right up until the point where it turns out those decisions you made were the wrong ones. The complete lack of direction given towards specific character builds ultimately made the difficulty of the encounters just too unforgiving. Min/maxing is par for the course in a hardcore rpg but Underrail seems to want to pull you in every direction at once - finally unlocked that door, ah sorry you were too busy upgrading your ability to create the weapons and skills to fight robots in the previous area and now those weapons and skills are completely useless versus dog mutants. Some people will call this a desire for hand-holding, but if you're not going to hold my hand while we cross the road for the first time you could at least give me a couple warning signs. Also - one monumentally daft idea is the option to choose either a classic or "oddity" XP system. Fell into the trap of picking "oddity" thinking it'd be interesting, well yeah all those items you need to find to get XP are locked up in boxes and lockers so you'll need to invest those already precious skill points into Hacking and Lockpicking now as well (and of course Sneak to bypass all those enemies you now can't compete with). It's a shame really, because what's the point in having a good story with meaningful choices when you get so bogged down save-scumming just trying to progress through each area that you forget what the whole point of you being there in the first place was?
Core gameplay on the tactical level is very similar to the newer XCOMs, with a variety of operation types on randomised levels and environments, and a smattering of special missions. Unfortunately the sheer number of standard operations that have to be carried out quickly causes tedium to set in causing the game to become a bit of a grind. This was not helped by the extremely repetitive soundtrack - some games have small soundtracks that just fade into background and that's fine but somehow this one was irritatingly noticeable. The strategic layer was a bit more involved and interesting than XCOM, but the progression system was very opaque and it wasn't really clear to me whether acquiring new tech was just completely random or dependent in some way on my actions. From hints given in abilities I'm guessing I never got to use a load of interesting poison and trap mechanics which is a shame but I had no idea when or how to unlock these! I thought this led to a dodgy diffculty curve where early fights are to be avoided at all costs because you have no gear and no abilities, and then later fights became essentially a tiring massacre of waves of enemies. The story is very low-key and doesn't have enough impetus to pull you forwards and so I ultimately gave up - I felt like I was ploughing in loads of hours and not really getting anywhere with the story. I can see that there were some good ideas baked into Phatom Doctrine but the bloated number of randomised operations and lack of sense of progress was a killer. I genuinely hope the devs make a sequel or similar game in another setting that is more streamlined because this had promise and just fell short of being enjoyable. (As an example of less being more - Shadow Tactics was only 12 "operations" and had me gripped right to the end)