PC gamers play on a variety of hardware configurations, from top of the line workstations on down to laptops over five years old. Developers must draw the line where they cut off support for less powerful machines that lack important features or just cannot keep up with the complex game simulation. This lengthy console generation has also reduced the pressure to upgrade, as ports rarely make full use of PC hardware.

In developing Retrovirus, we worked from the top down on the graphical detail. Our artists aimed for the best looking worlds and creatures that their high powered development machines could support, while the programmers kept optimizing to make more possible. But now that Alpha is going out to a wider audience, it's time to start expanding the hardware window.

Many optimizations can improve game performance without visual impact. Reducing shader instructions, hierarchical physics collisions, model instancing, and hidden surface removal can bring pixels to the screen faster without changing their result. But to really achieve compatibility with older machines, there is a point where visual quality must be dropped. In Retrovirus, advanced lighting techniques were a good place to simplify the calculations. Shadows, small decorative lights, and screen space ambient occlusion add lighting detail that is non-critical eye candy.

The image below shows a scene with our simplified lighting model. Hover over it to see the original high quality lighting.

The sweet spot for an action game is 16 milliseconds to render each frame, and on this development machine (a Radeon 5850, released three years ago) the original scene took 20ms. After lowing the lighting detail, it took only 15ms, achieving the target. Older machines could lower the resolution and drop anti-aliasing to keep up. There is a lot more optimization to do, but separating important visual features will give a consistent experience to all players.