Glimpse is the inhouse renderer of AnimalLogic. As many others, it is a unidirectional pathtracer. It was first developed to give lighting artists a fast feedback while the final rendering was done in PRman what always took some time because there were a lof of shadow map baking, bickmap baking before rendering could start.
Then step by step the renderer grew up and is now a full featured pathtracer which is used for delivering final renderings.
You can have a look at the Glimpse origins by developer Max Liani who described some early steps here: Glimpse blog.
fxguide has a great article about glimpse and reveals how the renderer internally works.
And another interview can be found on gc society.
Last update: 01.2021