In the vein of having an achievement system be tutorial-esque, i would prefer it's kept at more of a low level than that. Players respond better to immediate small goals that chain together, rather than making a long-term goal such as "become a ruler".
I would code small tasks "create a character", "place a character in the world", "take a knight's offer", "control a settlement", "set permissions on a settlement" etc. things that show you've found your way around some aspect of the game's interface. new task would become active whenever you complete an old one (some would be coded that you need to complete a different objective before they're available).
the point of having achievements is that they keep the player logging back in, so they need to be responsive and achievable right from the start. if you look at any system with "levels", then the first few levels (and/or tasks) are always really quick to achieve, then things gradually slow down. Having only things like "won a battle" don't serve that gameplay purposes, because you need to be playing too long to achieve that.
So ... basic design principles from any "level up" and/or achievement / badge system (they're effectively the same thing from a player psychology point of view) is to make them incredibly easy to achieve at the start, then gradually make them cost more work to achieve. You can signal this by categorizing them as bronze, silver or gold achievements. Winning a battle would be a "gold" badge, which making a character only nets you one bronze badge.
Having only long term badges such as for winning a battle or becoming king serves no purpose. Nobody is going to log back in who wasn't going to anyway because there's a badge for becoming king. But ... if they have a list of immediate tasks that they're told they haven't finished, then many players will log back more often to get those.
It also helps if there are separate tracks with overlapping goals. So, you've achieved one goal, but your halfway to getting another unrelated one. This is acknowledged by Sid Meier in the sucess of the Civilization series. They have separate milestones each with their own timers (producing units, making building, building wonders, your next tech upgrade, exploring), so you're never "finished" everything at once: you're always in the middle of a number of task. So you always feel "well I'm only a few turns away from producing XYZ so I'll keep playing" but then you achieve that next goal, e.g. producing a new technology, and you realize that then you're only a few turns away from building the Pyramids, so yet again you keep playing. having lots of small, little goals along the way is what leads to player retention. Promises of a big reward right at the end do not.
The only thing to watch out for is that if people are motivated by small frequent achievements, then you never really want a situation where they've run out of things to aspire to. Have some really difficult ones in there. You'd be surprised: if the goals just run out, lots of people will stop playing. However, if there are e.g. three near-impossible goals they won't ever feel like they've "finished" the game. Also you can do things like having repeat achievements for achieve "X" of something. e.g. you get a badge for having one vassal (per account), but then have that badge update to be to have 3,6,10,15 vassals (not at once, but across your entire account's history).
you can get clever about the type of behavior you want to encourage. e.g. if you have dungeon-exploring badges, and make ones for exploring 1 dungeon then 3,6,10,15 etc (pascal's number), then you're going to get a subset of players who go off dungeoneering a lot, who wouldn't do that otherwise. Hell, even counters that keep track of how many times you've done some tasks are enough for many players. e.g. if you had a stats page showing how many battles you've won / lost, how many dungeons you've ever explored, etc, then players will gear their playstyle to increasing those numbers. You don't need to get technical here, just take advantage of how silly us humans are.
