Lots of good games mentioned, picked up battletech with all dlc few weeks back and can not put it down.
decent story driven campaign, story missions plus random missions with lots of different variety, challenging missions. For example intel can show a easy mission but turns out to be a trap (long war esq)
You are free to go off and ignore campaign if you wish and build up your merc company. Loads of mechs from battletech universe, set 25 years before the clan invasion of your into the lore.
Also check out battle brothers in winter sale, really tough game. Random world generator, end game crisis. Set in medieval fantasy time.
You gotta build your merc company up from various different starts. Peasant militia, bandits, hedge knight etc.
Good looting system, some of the battle are solid which require you to use different tactics.
For example undead keep rising but if you chop their heads off they stay down. Goblins have low moral so break if you kill a few etc.
some battle can be irritating as some of the monsters are op, and can wipe you out if not careful.