I just got Tribunal and started playing it at 8 in the morning.

By 4:30 this afternoon...

• I have completed all of the quests that lead up to me killing Almelaxia
• I have completed all of the Crimson Plague quests
• Done a few sub quests
• Got the reward off of the king

Is there anything left to do? I find it ridiculous, even though I rule at Morrowind, that I completed it so quickly!

Hmm... have you done all the Imperial quests for the king? I think there are some of those you can do before you kill Almalexia. But, without starting a new character there probably isn't much more you can do, besides more side quests (I'm sure there are a lot more than just a few). Have a look around maybe?

Also, you could always go about and collect all the different artifacts for the museum and make a ton of cash, I suppose

There are 37 Tribunal quests in total, 21 of them miscellaneous. Most are very easy and take place in Godsreach.

Have you got the Mace of slurring, the BiPolar blade, the amulet of verbosity? If no to any of these you still have something to do.

There are a number of quests for the kings guard that follow the 'hunt the Dark Brotherhood' quest. These are optional. If you don't do them before the main quest you don't get the opportunity later. You probably have done them but if not it's something to do when replaying.

But I think even doing all of it, finishing in a day is not unusual. The same applies to Bloodmoon. At least with Bloodmoon you have got more to explore outside the quests.

Bloodmoon is much more easy going in my opinion, since its simply an extension of Vvardenfell itself. While playing Tribunal I felt compelled to stay in Godsreach until I had completed all the quests. While playing Bloodmoon I'd often go back to the main island to complete other quests, get training etc, simply because I got bored of all the snow.