Before reading my question, please see the following image, which is a pixel art representation of the battle against Ornstein & Smough, from Dark Souls:

(This incredible work was made by the deviantartist Cyangmou)

This is just one example out of thousands of incredibly detailed works made in pixel art.

My question is, can a game be made with this level of detail?

The closest I can think of is Death's Gambit, which is still an upcoming title. Still, it is not even close to the level of details you can find in some pixel art illustrations.

I am really curious to know if something like this would be viable. Of course, it is a lot of work, but pixel art games have framework to spare (as far as I can tell from experience developing and playing), it just would take very long to do it.

Can it be done? Sure, in theory. However as the years have rolled on pixel art has become less attractive for game developers (except for retro) because it doesn't scale as well as 3d artwork.

2 big disadvantages to pixel art:

1. As screen resolutions have increased, that's a lot of pixel pushing for every frame of an animation, and the expectations for fluid animation frame rates have also increased, not to mention the cost of edits, directions.
2. Memory .. you have to store all those animations. Do some calculations as to how much RAM you'd need to store / download for a large animated character with high frame rate.

3d on the other hand is wonderfully scalable. There is essentially not a lot of difference to getting a game working at 800x600 and at 4K (in terms of artwork). And 3d has loads of other advantages too, like you only have to make an animation once rather than having to redo the whole thing for every new direction / camera view, the ability to combine animations etc etc etc.

Thanks a lot for the answer, it makes a lot of sense, especially the screen resolution problem.

Do you think 2D games that have hand-drawn-like style (Hollow Knight, Castle Crashers, etc) have better advantages?