Heroes Chronicles: Warlords of the Wasteland
Heroes Chronicles: Conquest of the Underworld
Heroes Chronicles: Masters of the Elements
Heroes Chronicles: The World Tree
Heroes Chronicles: The Fiery Moon
Heroes Chronicles: Revolt of the Beastmasters
Crusaders of Might and Magic (Playstation and PC)
Heroes of Might and Magic: A Strategic Quest
Heroes of Might and Magic II: The Succession Wars
Might and Magic Book One: Secret of the Inner Sanctum
Might and Magic Book Two: Gates to Another World
Heroes of Might and Magic III: The Shadow of Death
Might and Magic VI: The Mandate of Heaven
Heroes of Might and Magic III: The Restoration of Erathia
Might and Magic III: Isles of Terra
Might and Magic IV Clouds of XEEN
Might and Magic V: Darkside of XEEN (and World of XEEN)
Might and Magic: World of XEEN (final quest) and Swords of XEEN
Might and Magic VII: For Blood and Honor
Heroes of Might and Magic III: Armageddon's Blade
Might and Magic VIII: Day of the Destroyer
Heroes Chronicles: Clash of the Dragons
Heroes Chronicles: The Sword of Frost
Warriors of Might and Magic
Might and Magic IX: Writ of Fate
Heroes of Might and Magic IV + The Gathering Storm and Winds of War

The games are listed in chronological order. MM 1-5 are arranged in the most obvious order. It is also possible that they may even take place before the first "Heroes Chronicles," and they can certainly be played first as the originators of the series (but if according to the chronological order of the plot, then rather as in the list). "Chronicles" are arranged by release date (except for Clash of the Dragons) and the events of these campaigns. Crusaders takes place before (and was released before) Heroes 4, Warriors - many years later after "Crusaders."

This is according to the NWC universe.