This is a version of Ironhand's graphic set that is up-rezzed to 64x64 pixels per tile, all of the creatures and living beings have been replaced by a 64x64 image of a chimpanzee: http://www.pixeljoint.com/pixelart/20754.htm
The base tileset has also been up-rezzed to 64x64 to see if there were any graphical glitches in the game.
As you can see from the active Adventure Mode save, all of the living things have been replaced by a chimpanzee. On my screen the Chimpanzee's high-details are not noticeable as the game seems to scale the image back to fit on the monitor in use.

This means that higher resolution graphics are definitely useless unless the target computer has a high enough resolution monitor to view them with. The game will always have a minimum of 80 tiles horizontally and 25 tiles vertically, so the resolution of the graphics pack must take into account the size of the monitor (usually something like 1920x1200) divided by [80, 25]. For 1920x1200 monitors, the highest resolution graphical tiles that would not be downsized by the game would be 20x20 pixel graphical tiles (assuming a square tile).