I worked with the concept artist to develop and select the blood decal textures, then handled the shading, placement and animation across the building. Readability drove most of the texture decisions. The game is almost entirely dark and lit by a handheld flashlight, so a decal that reads clearly in a bright reference shot can disappear completely in play. We tuned the shapes and values so they hold up when a narrow beam catches them at an angle, which is how the player will usually see them.

Getting the blood to actually read as blood was a shading problem rather than a texture one. Flat decals sit on a wall like paint, so I built specularity into the shader to give the surfaces a wet highlight, and pushed the look toward something thick and viscous rather than a thin stain. That wet response is also what makes the flashlight work in the decals' favour, since the beam catches the highlight and the blood picks itself out of the dark instead of getting lost in it.

The decals are projected onto surfaces, so placement took real care. A projection that looks correct head on can smear across a corner or stretch unevenly where it spans two surfaces at different angles, and I positioned and oriented each one so the result stays clean wherever it lands.

I animated the appearance with an alpha reveal driven by a mask, timed to Ben's actions, so blood arrives on the surface at the moment it should rather than being there from the start. The mask lets the shape fill in with some direction to it instead of just fading up as a flat block. That keeps the building changing as the player moves through it, and it means a hallway the player has already walked can tell a different story on the way back.