The game runs on the Divinity: Original Sin II engine, and is story-wise a more-or-less direct follow-up to that game, reuniting its six Origin Characters and the major NPC Malady in a new fight against the Bloodless. Gameplay-wise, it is a combination of Divinity: Dragon Commander's strategic gameplay and Original Sin duology's Turn-Based Combat, with you, as "the Commander", directing the main characters over the course of 60+ missions, which change considerably, depending on what you do.
The game contains examples of:
- Cutting Off the Branches:
- With Malady and all the heroes of Original Sin II alive and present, it's clear the choices that would have resulted in their deaths did not happen in the world state for Fallen Heroes.
- The good endings of each hero's personal quest seem to have become the canon resolutions; Lohse is demon-free and Lizard society seems to be raising dragonling eggs after the Red Prince brought back the dragons.
- Co-Op Multiplayer: Unlike Original Sin II (but like Original Sin I), only two players are allowed to play together, not four.
- Fantasy Gun Control: Averted for the first time in the series, with the Beast firing a musket in the announcement trailer, and the official website proclaiming that "gunpower comes to Divinity".
- Geo Effects: As per the norm for the Original Sin series, expect to create fields of elemental effects that will change the battlefield in all sorts of fun (and often explosive) ways.
- Mission-Pack Sequel: The game runs on the same engine as Original Sin II, with the main differences being the story structure and increased focus on tactical combat.
- Merging the Branches: In Original Sin II, you could only form a team of four and any of the heroes that you didn't bring would end up dead. Here, all six of them are alive (or unalive) and well.
- Old Hero, New Pals: Inverted. You play as the newcomer "Commander", joining most of the old cast from Original Sin II.
- Sequel Goes Foreign: Divinity: Original Sin II took place almost entirely in the human-settled portions of Rivellon, but Fallen Heroes takes the Lady Vengeance to the Dwarven Kingdoms and the Ancient Empire of the Lizards. An elven forest is also shown in the trailer.
- Story Branching: Both your narrative choices between missions and your performance in them unlock different missions down the line.
- Stuff Blowing Up: A new element, Sulfurium, deals "explosive" damage. Sulfurium surfaces appear to explode if anyone makes contact with them.
- Turn-Based Combat: The game brings back the Original Sin flavor of TBC, with Action Initiative, action points, and continuous terrain.
- The Undead: The Bloodless seem to be some form of undead — but not of the Eternal kind that Fane belongs to.