Lords of Magic (1997)
Not completely forgotten (it's on GoG), but pretty obscure, I think.
HoMM-like TBS on the world map, RTwP in combat. There's only one map (not even that big) that's spherical, if you start going west, you'll come back from the east eventually. There's a map editor, but it's pretty pointless.
You play as one of the 7 faiths fighting against the big bad god of death, but you can conquer everyone else too if you want. After beating the game you can play as death to conquer everyone. You choose a lord (mage/warrior/thief), that represents you in the game as a units, if you die (which is very easy) it's game over, unless you got another faith to be your vassal, then you can continue as their lord. At first you can't even buy units, you wander around your land and do stuff until you liberate your great temple.
The good: they included A LOT of stuff, you can trade with other faiths (with a complex system of attitudes and tones of parley), there are spies, stealing resources, taking and interrogating prisoners, spells research that depends on the level of your wizards, mercenaries, training units before buying them, fame and followers system, spells and curses that persist after combat, changing terrain with spells on the world map... also one of the main resources is ale.
The bad: most of it is either poorly implemented or inferior to just getting some resources and xp and conquering everybody. Also the game is buggy as hell (often in interesting ways, I once was given control of enemy units after a battle). AI sometimes goes completely retarded for no good reason, but it's all so poorly balanced and content-rich that it's still fun just for exploring random high-level neutral dungeons and seeing what you can do.
The soundtrack is great too.
Evil Islands: Curse of the Lost Soul (2000) - probably the first real 3d rpg (at least one year before Neverwinter Nights).
stealth approach is feasible however the combat/spells and crafting system are exceptional.
More like mandatory, especially on hard most enemies annihilate you in normal combat. Crafting was really great though. The graphics were pretty amazing for the time too.