Oldie RPG with the added bonus of an included editor
Ambush at Sorinor knows that it isn't the most original or focused on story RPG out there, and to sort of make up for that, it does two things: it allows you to play the game disconnected from the main campaign, in small, mission based chunks, and it then allows you to experience the game via your own missions, which can be started and designed from scratch or just edited form the game's already existing ones, modifying them as you see fit. This is your regular, day to day party based RPG of the early 90s type, and so expect some inconveniences, a control scheme that may not feel as intuitive as you'd like to be and many other small qualms. But, at any rate, if you're in for that kind of epic journey, in small chunks or in one campaign form, you can have your way with it, no issues to be expected. Alternatively, try Warlords 2, offering you both RPG as well as a more chunky strategy bit (without the ability to edit your own levels, though). What I like about both is the chivalrous nature of the worlds crated and their nicely done, sturdy, structures.