Necroing my own thread to show off what I've recently found.
Solid and Shade is a mod for Mount and Blade (classic, not Warbands) that lets you be a necromancer. You learn necromancy from the definitely evil Blood Fountain of Death.
It still has the standard Mount and Blade headcount limit but you can turn corpses into zombies from your camp menu. Corpses are items and a randomish number of then are available to loot after battles. Prisoners can be sacrificed for a more reliable source of corpses intact enough to reanimate. In addition to reanimating them into zombies, corpses can be harvested for parts that are used in crafting. Crafting is unlocked in tiers and to get to the next tier you have to craft one of each recipe in your current tier.
Zombies rank up, have morale, and require weekly payments like standard units in Mount and Blade. The payment is written off as "maintenance fees" in the mod's FAQ. At higher crafting tiers you can summon demons and shadows, and craft golems.
One big problem is the loot system. There's a maximum number of items that can be in the loot window in Mount and Blade which limits how many corpses you can get per battle. The base game and mod are not designed for leading an unstoppable undead horde of thousands, so a couple dozen higher tier monsters has to make do.
Also:
Ray's the Dead is a game that seems like it'll be like Pikmin, but with zombies.