The Nostalgia-Craft Texture Pack is essentially a rather faithful recreation of the textures from early versions of Minecraft, as well as the current, (outdated) in-browser, free version of Minecraft. For those who didn’t start playing Minecraft until the later and more recent updates started rolling in, you can consult the screenshots below as a point of reference, because this texture pack stays very true to the source material. However, for those who still need an explanation, basically the grass was much lighter in old Minecraft, trees were almost see through (the leaves), and essentially other small changes along those lines.
While these changes may not seem like much, they hold a special spot for some. In this day of Minecraft with all of these new-fangled additions being made, just seeing these textures bring the old school players back to the days of simpler Minecraft, when it was largely unheard of. It serves as a time machine for some, while just new textures for others.
Now for some screenshots of the texture pack.