Stingray's built-in rendering pipeline uses deferred shading. The classic standard method of antialiasing used in realtime graphics, MSAA, does not work very efficiently in a deferred rendering pipeline. Additionally, MSAA only reduces aliasing on the edges of polygons, and physically-based rendering such as the kind used in Stingray can have aliasing from many other types of sources, for example, specular aliasing on shiny surfaces. MSAA will not help with that.
Stingray uses a variation of temporal anti-aliasing (TAA or just temporal anti-aliasing). It takes pixels rendered from one frame and re-uses them in future frames. It can do this because it tracks the movement of all objects in the game world. Additionally, the viewport is always being moved around in a sub-pixel pattern. It's a bit like rendering at a high resolution and then scaling the image down to reduce aliasing, but spread out over time. Temporal anti-aliasing reduces specular aliasing as well as geometric aliasing.
The major drawback of this technique is that if things are moving across the screen quickly, you have to throw away old pixels more quickly, otherwise everything becomes a blurry mess. The good news is that you tend to notice aliasing less when things are moving. But it's still a tradeoff.
Most modern game engines use this technique to some extent. Unreal Engine 4 relies solely on temporal anti-aliasing for all of its antialiasing (on desktop and console, not mobile). CryEngine uses a combination of SMAA (pattern recognition post-process) and temporal anti-aliasing. Unity, for example, doesn't have any anti-aliasing apart from post-process FXAA/SMAA1x unless you are using the forward rendering path with a gamma buffer (no HDR, because MSAA requires special treatment to work with HDR, and Unity doesn't support that.)
In theory Stingray supports being reconfigured to use a forward rendering pipeline, in which case TAA could feasibly be combined with MSAA to produce better geometric anti-aliasing during movement. However, it doesn't ship with support for this. I'm hoping it will in the future 🙂
