Astronaut is an action-based flight simulation game that challenges players to navigate a plane while avoiding incoming rockets. The game consists of five progressively difficult levels, each with increasing rocket speed and frequency. The player controls the plane via a joystick, maneuvering through the rocket barrage to survive for a set amount of time to progress to the next level. The game includes boosters that can be activated to provide temporary advantages, such as a brief period of invulnerability or slow-motion to assist in avoiding obstacles. The goal is to outlast the rocket attacks and move through all five levels.