Avadon: The Black Fortress is an isometric RPG by Spiderweb Software, known for a huge lineup of other classically-styled, exploration-focused roleplaying games. It's very similar.

A true roleplaying game

The game's pacing is quite slow, and this is generally intentional: though there are hundreds of items and dozens of spells to use, the game expects you to slowly canvas and learn about its world, taking in lore, solving puzzles and gradually growing stronger. Though you're a servant of the crown, that authority can't be used to bludgeon your way past every obstacle: there's lots of problems to solve, and often, multiple ways to solve them. The game's story even features multiple endings.

An Ultima-te game?

Overall, Avadon: The Black Fortress is as much an experience as any classic Ultima game would have been at the time of its release and beyond. You will control your avatar in a number of thrilling situations, learn about the world, and puzzle out how best to use your steel, magic and wits to progress. The game can be tough at times, but to fully enjoy it, that should be part of its appeal to you.