Back to cooldowns. They suck because in most games that use them you end up cycling through them from the most powerful to the least until the enemy dies or you die. Every battle.
In Underrail you don't get to cycle through. You have 1 or 2 turns (in serious fights) before your wiped. And you have maybe 8 options available to you (on cooldowns). You have to choose witch 2-3 maybe 4 out of those eight will get you alive through those 1-2 turns without dieing and prefferably killing the enemy. That's why the system works. Would another system automatically achieve a better result. IMO no. Because this is about as good as CRPG combat gets. Would another system achieve the same quality. Of course. Would it necessarily surpass it. Not really.
A lot of battles are not resolved in 1-2 turns. I guess battle length can vary significantly with different builds, because on my crossbow/throwing character I am 1-2-3-1-2-3 cooldown cycling quite frequently. Yes, there are still important choices to make, but they are quite limited to what a more flexible system can provide, especially after the opening turn or two you're increasingly stuck into a static cooldown rotation. Thankfully not everything is on cooldown so it's not as bad as it could be, but there's definitely room for improvement.
I don't think it has anything to to with the systems but with the single char combat which automatically limits tactics/strategics. Mind you, we are not even comparing it to better predecessors, since nearly every CRPG I played in my life has weaker combat than Underrail. Right now we are just following the old Codex habit of comparing it to PnP roots (don't apply, it's a CRPG, no GM, needs to add some balancing, different beast entirely) and the dream RPG in our heads (which often only exists in vague and nebulous form, but we know it exists somehow and it's awesome of course, just like us ^^).
This will never be a new UFO: Enemy Unknown or JA2, even with a different special ability balancing system or even more abilities to choose from. But it doesn't need to be, since those single char CRPGs have a big advantage over party based games that also applied to Fallout and made it that great: The char development decisions you make can have much more impact, since there is no party that cushions your failings to level a character optimally for the job you want him to do. So that aspect of the game feels like a game again, with choices and consequences and the possibility to lose or at least have it hard at some point in the game because your illiterate Int3 tribal cannot into reading.
Party based games can still be a lot better in the combat department though (since they can reward the player for finding combinations of very specialized builds that boost each other and still have the squad tactics game on top of that) but sadly they usually aren't.
Btw I'm playing on hard and
Lord Andre might have exaggerated a bit but I think his argument still stands. You and the enemy are both quite squishy (a thing most good games seem to have in common), so the fight is deadly and over in maybe 5 or six turns against harder enemies (1 or 2 against trash mobs). And I can rarely cycle through special abilities in that time, it's usually combat preparation (traps, some buff) followed by enemy disablers (molotov, telekinetic punch, net and so on, the list is long) and then by special attacks tied to feats. Maybe another round of disablers later but that's it.
It's not overly strategical since that basic order stays the same for most encounters, but the way all those nifty systems interact with each other elevates it to something better.
There are a lot of decisions to make (also depending on what options your build offers of course):
Should I use the hammer or the gloves? DT anyone?
Is that enemy resistant against psi disablers?
Does it help to reduce that enemy's strength?
Is that special attack I have there context sensitive like make it bleed with a lot of knife stabs and only then eviscerate?
Which enemy in the group is the most dangerous? If they all are dangerous, which one can I eliminate in the first 1 or 2 rounds?
Is there a chokepoint and can I use it to my advantage? (psi wall, traps, molotov, ...)
Melee or ranged enemies? If ranged, what weapon type (equip another armor or shield emitter before combat)?
If melee, can I kite them? Do I have to use a trap or net or feat to pin them down to keep them at distance?
Which trap will work best on that enemy type? What kind of special bolts? Should I put another item on the belt that might come in handy during the encounter?
Might there be stealthed enemies around? Better throw a flare or 2...
and so on
So the systems are very solid and make it surprisingly fun for a single char CRPG. Much more fun than the braindead go for the eyes Fallout combat imo (which was still fun just like Diablo combat can be fun even though it's dumb).
Anyway, I rarely get to cycle through abilities since I have to react to my rapidly dwindling health (did I mention enemies are deadly). I even have to retreat after killing 1 or 2 enemies from a group quite often.