Flying

The game utilizes fractal technology to create the craggy mountains of an alien planet, where the visilibility was drastically reduced by the dense atmosphere. The player controls a fictional "Valkyrie" space fighter (converted for search and rescue duty) from a first-person view, attempting to land and pick up downed Ethercorps pilots. Some of these mountains hold anti-aircraft guns, which have to be avoided or destroyed. Due to the varied terrain, the direction finder has to be used to locate the pilots, whose visual beacons are often masked by mountain ridges.

At higher levels, the enemy Jaggis begin flying kamikaze saucers. The mission area also moves into day/night boundaries. Night missions are particularly difficult, requiring diligent use of the altimeter to avoid crashing.

Flying consumes fuel. The way to replenish this supply is to rescue downed pilots who bring their remaining fuel supplies on board.

The thick atmosphere is sufficiently acidic that downed pilots' craft were being slowly disintegrated. An exposed pilot's survival time outside his craft is less than a minute, due to his flight suit and helmet literally dissolving. This makes it imperative that the player rescue pilots as quickly and efficiently as possible.

Rescue

After landing within sufficient "walking" proximity to the pilot, the player shuts down the engine, also turning off the ship's shields. Turning on the engines prematurely would incinerate the exposed pilot and the sheilds would prevent him from entering the ship. The downed pilot then disembarks his crashed ship, runs down to the Valkyrie's cockpit, and knocks on the crew entry door; the player can then open up and let the pilot in to complete the rescue. Failing to open the door kills the pilot; his knocking on the hatch becomes at first frantic, then slower and more feeble as he perishes in the corrosive environment.

As an amusing twist on this relatively straightforward premise, added at the suggestion of George Lucas, some of the "pilots in distress" are actually hostile aliens in disguise. After landing near a downed pilot, the player watches him run off-screen, and then has to wait for several tense seconds—if it were human, the familiar, frantic "tap-tap" noise would be heard from the ship's hatch; otherwise, the alien Jaggi would suddenly jump back into view, sans helmet, roaring and trying to smash into the cockpit. Unless the player restores the ship's shields, the windscreen cracks open and the pilot is killed. Likewise, inadvertently letting a Jaggi pilot into the player's ship has disastrous results - it begins to dismantle the ship. In early levels, the Jaggi can be distinguished by their green heads versus the white human helmets. However in later levels the aliens evidently learn to don the human helmet and become identical in appearance. This, along with an unpredictable pause between the human/alien approach and the tap-tap/alien jump makes for a very tense experience. According to head developer David Fox, this shock moment made Rescue on Fractalus! "the first [computer] game to really scare people".

Prior to release, Rescue on Fractalus! was named Behind Jaggi Lines! during development. This name refers both to the Jaggis, the fictional race of hostile aliens in the game, as well as the lack of spatial anti-aliasing in the game's graphics, resulting in jagged diagonal (or curved) lines, colloquially known as "jaggies".

The Atari 8-bit versions of the game featured an intro screen depicting the pilot's mother ship.

A poster of the game appears in Zak McKracken and the Alien Mindbenders.

In 2004, an unreleased prototype of Rescue on Fractalus! for the Atari 7800 was found in the possession of its original programmers. While most of the core elements of the game were intact, the project was cancelled before the gameplay could be completed. The 7800 version would have taken advantage of the system's better graphical performance to produce a much smoother simulation of the planet Fractalus.

• Lucasfilm Games
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• The Eidolon
• Koronis Rift