U.F.O.

U.F.O. is a single player variation on the Space Invaders genre.

The player controls a fighter aircraft, a U.S.A.F. F21 Codor, the only plane
that is capable of defending the Earth against an alien onslaught. The player
has only four of these planes / lives with which to complete the game.

The plane can be moved left and right as well as, to a limited degree, up and
down. The F21 Condor has a gun with which the player must shoot alien ships
that are attacking Earth. However, this gun will overheat and jam if used too
much so on the right of the game screen is a temperature gauge that the player
must monitor.

When all enemy ships have been cleared from a level the player must fly their
ship to the next level through a hypersonic air corridor to the next combat
zone. Here, against a flashing background, the player must keep their craft
within the bounds of the corridor as it gently winds its way to the horizon.

After a successful transit the player can spend credits that have been earned
on either their shields or their energy before entering the next phase of
combat.