From the official website (infinitythegame.com):

Infinity is a tabletop wargame in which sci-fi themed miniatures are used to simulate futuristic skirmishes.

Infinity recreates Direct Action operations, high-stakes missions in the battlefront or behind enemy lines, where victory or death are a trigger pull away. Players command a small group of elite soldiers, chosen for their adequacy to the mission parameters at hand. Each battle calls for a different composition, and building an effective team from hand-picked members of different regiments is key to a successful operation.

Infinity is a groundbreaking, dynamic system that allows you to make meaningful, fun choices throughout the entire game sequence, and gives you the tools to implement any number of strategies with realism and flexibility.

The Infinity Core Book contains everything you need to play and explore this futuristic universe: the full rules, detailed background on each faction and unit, troop profiles and lots more.