I don't know for sure as I didn't create those pieces. It appears to be quite flat shaded, which leads me to believe it wasn't done with any 3d renders, except maybe as reference material to get poses right or something similar.
General pixel art is time consuming. But I doubt that game was made with a single person, rather probably at a minimum programmer, artist, and musician, over a lengthy period of time. Remember that it is possible to pixel out anything you want any size you want, given both the time and the skill. Fighter game sprites used to have resolutions of over 100x100, with animations that were quite fluid, though they took much time to do and do right.
Last thing I mention about that game, notice how much of the color is in chunks. The environment as well as the character are made of mostly single colors for things. There isn't much shading going on. In that style, I would think that it wouldn't matter as much how big the pieces are because the actual work wouldn't be as much as on other styles due to using the same color in big chunks.