Baldur's Gate 3 does not run on Unreal or Unity. It runs on Larian Studios' own engine, the same lineage that powered Divinity: Original Sin and its sequel, developed and maintained in-house over more than a decade.
Short answer
It uses the Divinity engine — Larian's proprietary technology, evolved across the Divinity: Original Sin games. That choice is why surfaces, elevation and physical interactions work the way they do, and why the game supports drop-in multiplayer and split screen.
Why an in-house engine
Larian's games are built around systemic interaction: water conducts lightning, fire spreads along oil, a crate can be stacked, thrown, or dropped on someone. Systems like that are far easier to build when you own every layer of the engine rather than working within someone else's assumptions about what a level is.
The company had also already spent years on this technology for the Original Sin games. Baldur's Gate 3 is the third major title on that foundation, which is a large part of why a studio of its size could ship something this big.
See also: Baldurs Gate 3 Gog — the closest BG3 answer to this one.
What the engine is visibly good at
- Surfaces and elevation. Nearly every combat encounter is built around height, and surfaces persist and interact. That is engine work, not level design.
- Physical objects. Almost everything can be picked up, thrown, or stacked, and the game accounts for it in combat maths.
- Save-state complexity. The game tracks an enormous amount of world state — who died, what moved, which barrel exploded — and restores it reliably.
- Multiplayer and split screen. Both were designed in from the start rather than bolted on, which is why they work in a game this systemically complex.
See also: Baldurs Gate 3 Acts — the closest BG3 answer to this one.
What it costs
Proprietary engines are expensive to maintain, and they come with fewer third-party tools. The trade shows up in places: the game is CPU-heavy in dense areas, particularly the city in the third act, where the number of simulated actors is enormous. That is a systems cost, not a graphics one — dropping visual settings helps less than you would expect.
Modding is another consequence. The engine's tooling is Larian's own, so the modding scene developed around whatever the studio chose to expose rather than around a widely known public toolset.
See also: Cyberpunk 2077 Engine — the same question, but for Cyberpunk 2077.
How it compares
| Engine | What it optimises for |
|---|---|
| Divinity (Larian) | Systemic interaction, persistent world state, turn-based combat with physics |
| Unreal | Visual fidelity and broad third-party tooling |
| Unity | Iteration speed and platform reach |
| Creation (Bethesda) | Dense object persistence in real-time open worlds |
None of these are better in the abstract. They are answers to different questions, and Larian's question was "how do we make a world where players do things we did not plan for".
Why it matters to players
Mostly it does not — until you throw a barrel of oil, ignite it with a cantrip, and watch the fire spread down a slope into a room you have not entered yet. That behaviour is not scripted for that encounter. It is the engine doing what it was built for, and it is the reason Baldur's Gate 3 feels less rehearsed than most games of its scale.
Baldur's Gate 3 FAQ
Is Baldur's Gate 3 made in Unreal Engine?
No. It uses Larian's own Divinity engine.
Is it the same engine as Divinity: Original Sin 2?
The same lineage, substantially developed further for this game.
Why is my frame rate low in the city?
Act 3 is CPU-bound because of the number of simulated characters, so graphics settings help less than a faster processor would.
Can the game be modded?
Yes, using tools built around Larian's own formats, with official mod support added after launch.
The engine is the reason the game's best moments are the ones nobody designed — including the ones that go badly.