UFO! is an action-adventure game where you command one of Earth Federation's robot-controlled battle cruisers to protect the planet from an invasion of unidentified flying objects. The ship is equipped with a laser cannon and a force field, which can be drained when firing lasers.
The gameplay involves navigating through space and destroying UFOs that are drifting randomly or moving in groups. There are three types of UFOs, each with its own weaknesses and difficulties. You must use your laser blasts and the ship's force field to destroy them before they destroy you.
As you progress through the game, you'll earn points for each type of UFO destroyed. The points increase as the difficulty level rises, making it a challenging experience.