For me personally, I need to get my character skill to a certain level, for example, I would like my mage destruction or conjuration reach lv 100 before I actually head into the main quest or some other major quest beside the College quest I'm trying to finish right now simply because then I would have really overpower ability to actually feel like a god and taking time exploring dungeon and messing around a bit. Without being overpower, I don't feel like I would want to take time going through the quest and exploring because I would have to worry about dying too much and not being strong enough for certain boss. Just my opinion of being an accomplished and overpower god in Skyrim

What's your definition of being accomplish?

Making the most bada$$ character that i can ?
Making the most beautiful/handsome character that i can ?
Screw the mod out of skyrim with CK ?
Playing to death to satisfy my hunger for this game ?
Troll the NPCs in my travels .
Gather gold bars,gems,pretty clothes,robes,armor,weapons ?
And many other things that i want to try on this game for years to come.

Accomplishment? I guess finishing the main quest is all I can really say as accomplisments in games mean nothing to me.

I play Skyrim (and games in general I guess) for satisfaction rather than accomplishment. And satisfaction for me comes from NPC interaction such as adrenaline inducing and unpredictable fights and interesting dialogue and plot twists. Also 'trolling NPCs' as mentioned above

Whenever I save a prisoner.

I go for the generic accomplishments that every RPG has, I mean, why else play the game?

I develop 3 characters modeled after the main archetypes, then accomplish a couple things.

1. Finish Main Quest
2. Finish guild, get what I want from guild, do the same for other guilds.
3. Get best equipment I can find, then find joke equipment to screw around with.
4. Pick Side Quests for reward or roleplay. (Daedra, Civil War, Forsworn, Bards, etc.)
5. Buy House(s)
6. Buy/Get Horse
7. Get Married (Or not)
8. Fill up a chest with weapons, another with armor, potions, poisons, food, books, etc.

Each one of those is an accomplishment for any character I make, and roughly the same for every RPG I play outside of TES.

Now, if I manage to do all that on one character... well I've done everything I need to do and I'll just leave my less developed characters for days when I'm bored with other games.

Whenever I can completely make it through a bandit fort and wipe the place clean without the Sneak eye opening at all.

i dunno, done the main quest, was [censored] all. and i'll be honest, cant be bothered with all the side quests.

stopped playing the game for abit. i do this so i dont get sick of it.
dont get me wrong, its a good game!!