HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

Firstly, the skeleton feature is for HD+, not for HD. Secondly, it doesn't affect the gameplay; it just reduces the hassle of managing a free slot. It doesn't increase the player's capabilities, but it does reduce the chance of making a mistake due to carelessness. Moreover, some of the features in HD+ do affect the gameplay – gems in the Nagash units, fixing the quick spell bug, and fixing the Berserker bug.