A roleplaying megadungeon of alternate realities
From the introduction:
Astulae is an open-system roleplaying or storytelling game: it is not specifically targeted to any particular system and can (and should!) consequentially be adapted to suit most.
Astulae (a plural) is Latin for “splinters”. At a basic level, each “room” in Astulae is splinter of reality taken (and sometimes frozen in time) from across a grand ensemble of possible parallel realities. Somewhat akin to pocket dimensions, each Astula (singular) can have its own laws of physics, its own peculiarities, and sometimes: its own denizens – some benign, some deadly, and some incomprehensible.
The product primarily is a developed multi-genre setting presented in a system agnostic format. For players who do not desire to adapt the setting to a third-party rules system, the product also contains a simple dice pool system called the Collaborative Gaming System.