A thruster is a device that produces a force to push or propel something forward. It is commonly used in space travel and underwater vehicles to create movement and control the direction. Full definition
The movement system is getting a change with the utilization of thruster packs. (joystikrevolution.com)
Also, you use thrusters during low gravity segments to get through levels. (cogconnected.com)
Visceral has also added a couple of new functions to Isaac's suit, including thrusters for use in zero gravity environments, giving you full control of where to go as opposed to simply zipping towards a point in a straight line. (gamingunion.net)