Well, considering Minecraft is predominantly voxel based, polygon recreations of items like pickaxes, swords, armor etc are actually quite perceivable. Other such accessories such as a diamond ore pendant, Enderdragon wings, a dragon egg necklace, hell even a diamond necklace. The great thing about Minecraft's art style is it's so recognizable and exploitable. So those would be my next recommendations. Items for your character to fit the theme. And from then on in, things such as small clusters of smoothsone to replace the existing rock models, (If you're lucky, make them match Feralheart's TERRIBLE cuboid collision geometry) flora textures from the game to replace Feralheart's more 3D flora, and even a code to remove the terrain smoothing that causes the painfully triangular terrain, and just keep it as a series of steps.