The Painkiller franchise holds a special place in the hearts of boomer shooter fans, known for its fast-paced action, unique movement mechanics, and gothic horror atmosphere. However, as the industry moves forward with newer engines like Unreal Engine 5, Painkiller: Black Edition (2004) and its classic multiplayer scene are left behind—stuck on a proprietary engine with no official updates.
A recent discussion in the community has brought up a compelling question: Should PainEngine and its later iteration, NecroEngine, be open-sourced?
The Legacy of PainEngine & NecroEngine
PainEngine powered multiple Painkiller titles, including:
- Painkiller: Black Edition (2004)
- Painkiller: Overdose (2007)
- Painkiller: Redemption (2011)
- Painkiller: Recurring Evil (2012)
NecroEngine, an evolved version, was used in NecroVisioN (2009) and its sequel NecroVisioN: Lost Company (2010).
Despite its age, the engine still holds up visually and mechanically, thanks to an active modding community keeping it alive with projects like Painkiller: Reload, NecroGenesys, and Revenge of Belial.
Why Open-Sourcing Would Be a Game-Changer
The biggest limitation right now? Painkiller: Black Edition’s source code remains closed. While modders can tweak game scripts, they can’t modify the core engine, limiting potential improvements. If PainEngine were partially or fully open-sourced, it could:
- Enable fixes and updates for modern systems.
- Improve netcode and movement mechanics for multiplayer.
- Allow modders to replace proprietary components (e.g., swapping Havok Physics for an open-source alternative like NVIDIA PhysX).
- Revive the competitive scene, which thrived in CPL tournaments (2004-2005).
The Problem: Who Owns PainEngine?
One of the major roadblocks to open-sourcing is uncertainty over the engine’s ownership. Since Painkiller: Hell & Damnation (2012) moved to Unreal Engine 3, it’s unclear who holds the rights to PainEngine and NecroEngine today. Without a clear legal path, fans are left hoping for a goodwill release from the current rights holders.
A Tale of Two Painkillers: Black Edition vs. Hell & Damnation
While Hell & Damnation was intended as a modern remake, it simplified many mechanics, alienating fans of the original’s high-speed, skill-based gameplay. Multiplayer, in particular, was a disappointment, lacking the depth of the original PK++ mod used in competitive play.
This divide further highlights the need for modders to have deeper access to the original Painkiller’s code—something that could be achieved if PainEngine were open-sourced.
Final Thoughts: A Lost Engine with Huge Potential
While a full open-source release is unlikely due to proprietary tech like Havok Physics, a partial release could still be incredibly beneficial. If the community had access to the engine’s core, they could work around missing components and modernize the game for new hardware and online play.
The only remaining question: who can make it happen?
Should PainEngine be open-sourced? Let us know your thoughts in the comments! 
This would certainly be cool.
I returned to Pain modding after more than 10 years, and was surprised by the amount of cool things that have gotten released since, and how much capability it still holds compared to other engines I have worked with.
Fingers crossed to make this happen!
Definitely it should be open at least partially. I still have a hope to see this sometime in the future. It’ll help to upgrade the engine netcode. The mutiplayer in Painkiller is awesome but the netcode is what turns off a lot of people from multiplayer. By the way, the open code will help to release the COOP mode. We have people around the community that could handle it.
The question really is: whom to ask or sing a petition?
PLEASE make it open source. After so long, I think it would open up for some great mods, and innovations to improve on the code. Given the state of AI and coding development, I think it would open the door to allow the PainEngine to live on.