OpenBlood2

OpenBlood2 recreates Blood II: The Chosen on a portable engine. The original gameplay code was available, but the engine code was not, so the foundations needed to run the game had to be rebuilt.

Recovering the data, then the game loop

I began by reverse engineering the assets. Blood II’s DTX textures needed special handling, despite converters already existing for other variants of the format. ABC models and levels came next, eventually leading to a scene viewer.

It took four iterations. The first reused the gameplay as an external library, then linked it statically, but ran into differences in pointers and virtual function tables. I then explored a new SDL3 engine with OpenGL 4 and OpenXR, followed by a Godot prototype in C#. These versions helped move the project forward while revealing the difficulties of rewriting the game’s behaviour from scratch.

The current version returns to the first approach: preserving the loop driven by the original code, with extensive changes for 64-bit systems and ARM64. This work eventually produced a playable version.

An older game on current platforms

OpenBlood2 runs on Windows, Linux, macOS, Android, iOS and Meta Quest. It supports current screen resolutions and aspect ratios, as well as keyboard, mouse, gamepad, touch and VR controllers through an input action system.

Enhanced Renderer mode adds PBR rendering and post-processing effects: bloom, GTAO ambient occlusion, SSR reflections and tone mapping. OpenXR integration brings virtual reality support with options suited to that experience. Multiplayer works over a local network or with a headless dedicated server.

The project combines game preservation, low-level development and new rendering capabilities, while keeping the original gameplay code as its reference point.