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

“Complete” editions also come in different versions, and it’s possible that you are installing one version on top of another or patching incorrectly. The inability to see mana as a trail has been present since version 3.0 and the localized versions of 3.2. This is caused by the file GENRLTXT.TXT, which was published here.
In the English version, Cyrillic characters are not included in the fonts, and Windows is not configured to use the correct substitute font. Therefore, gibberish is displayed. The simplest solution is to place Cyrillic fonts in the Data folder.