CRUX is Ill Gotten Games' in-house tabletop roleplaying and wargaming system. Designed for modular use in any genre, every CRUX game is cross-compatible any other, so you can play in worlds you like or mix and match parts to create your own.
CRUX uses a single set of common polyhedral dice (d4, d6, d8, d10, d12, and d20). Gameplay revolves around rolling a "CRUX die" (starting at a d4, but "leveling" to higher dice as the character becomes more experienced) and adding a modifier based on their abilities. We built our system with a mind toward real-world plausibility, with fantastic elements (magic, monsters, weird science) skewing those values into the realms of the outrageous, all while being simple enough to fit into a 63 page rulebook.
This book doesn't come with a pre-baked setting, but is a launchpad for your own ideas, and includes elements from a smattering of genres to give you a point of reference when creating your own content.
The CRUX: Universal Roleplaying rules are 100% compatible with their sister-rules set, CRUX: Universal Wargaming (featured on the reverse side). The two can be used in tandem, so you can swap characters between them, or weave integrated campaigns that switch between roleplaying and miniature wargaming using any miniatures you like.