has often been likened to Asteroids and . What is mentioned less often is that it is basically an inverted Atlantis: Instead of defending a planet surface against space ships, the player is doing the attacking in this case. In a star system, several planet surfaces need to be stripped of their defenses. The catch: gravity.
Already on the system level where the ship is basically controlled to select the next planetary level, the player is inescapably drawn towards the biggest mass in the vicinity: the deadly sun. Entering the vicinity of one of the planets, the game zooms in on its surface. Here, defending bunkers (and ships) need to be destroyed while collecting blue canisters will refill the player's fuel tanks.
Now consider this: How do you shoot a ground target right below if your gun is located in the front and the thrusters at the back of your ship? Sure, you just turn around and aim downwards – but what happens after you've destroyed your target? In this game, you will be spiralling right into the ground, unless you manage to turn quickly and reach escape velocity again.
uses this concept to design some devious levels which are much more about careful navigation than quick action on the trigger. Case in point being the reactor challenge: Flying into a sort of snail shell, the player has to destroy just one target at the very centre and then escape before the countdown runs out. With each cleared galaxy, the time limit decreases, of course, so that things stay challenging even for experienced players.
The Atari 2600 conversion went relatively well. Maybe because the arcade original did not depend too much on flashy graphics in the first place, things only got a little bit more blocky. The space in which the player can navigate feels a bit more cramped, which actually increases the difficulty a bit, but the game is still very playable – most importantly because the gravitational model with its inertia effects has been carefully recaptured. So this particularis well worth your time!