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In 1986 realistic physics in videogames were a pretty rare thing. It was often a struggle to get an 8-bit micro to move sprites around smoothly and scroll the screen without throwing in a load of maths straight from a Physics textbook. However Jeremy Smith managed this with some style in a game that could be described as Lunar Lander bammed up to the max.
Jupiter LanderLunar Lander was a game often supplied in program listings in magazines or on a computers welcome tape and must have appeared on every kind of computer around in the early 1980s. The idea of the game was to gently land a lunar module on a flat area of the moons syrface by firing the crafts thrusters to steer and counter the effect of gravity. An example of this kind of game can be found in Jupiter Lander on the Commodore 64 and pictured on this page.
Another strong influence on Thrust was the 1982 Atari game Gravitar which had you visiting planets to destroy a reactor and then escape. As indicated by the name gravity played a large part in this game too. Pulling you down while on planets and in towards the star when travelling between planets.
Thrust's gameplay is based entirely on its physical model. You pilot a craft with three controls for movement: rotate left, rotate right and apply thrust. At the start of each level your craft will be floating above a planet surface - I say floating but within a second floating will turn to falling as gravity takes a grip. From this position the aim is to pilot your craft to the bottom of the cavern that is to be found on each planet surface. The caverns start off simple with wide tunnels and few rooms however they soon become maze like and very tight making precise control of your craft important. Further complicating your descent through the caverns are gun turrets and doors. Fortunately your craft is armed with a gun of its own to take out the turrets and which you'll also need to open the doors by shooting a switch. You also have a shield which you must manually activate and while this is in use your rate of fuel consumption will increase. That given you'll probably also find yourself running out of fuel from time to time particularly on the later levels and you'll need to pick up some fuel to replenish your supplies. You can do so by hovering over one of the marked fuel containers and activating your shields.
Video of level 2On reaching the bottom of a cave you'll find a power orb sat on a pedestal and this is where the games physics really shine. The aim of each level is to pick up the orb with your tractor beam and navigate back to the surface and out into space. Sounds simple enough? It would be if the orb didn't have mass and momentum of its own. The tractor beam acts like a rigid pole that can pivot freely through 360 degrees at each end. And so as the orb starts to swing around your own craft is pulled and jerked with it (the best way to see how the physics work is to play the game or watch the video to the right). Trust me when I say that those tricky tight passagese I was talking abot earlier are going to feel even tighter now. If the games collision detectioon wasn't perfect then it could get frustrating quickly however it really is absolutely pixel perfect. As are the physics - you'll literally feel yourself losing control of the orb and there will be a few seconds of frantic grappling with its momentum and deesperate use of the thrust button before you are dragged into a wall. Each and everytime you crash (and you'll do this a lot) it will be no ones fault but your own and you'll know it. If and when you do make it back to the surface bonus points can be scored by destroying the power plant but yet again this is easier said than done: as you try and get a clear series of shots in the orb swings around yet more.
There are 6 levels in total in the game but when you get to the end of those levels (feeling rightly proud) Thrust has one more trick up its sleeve. Play the same levels again with reverse gravity. It sounds far simpler than it actually is. After hours spent mastering the caverns and perfecting the timing of your thrust everything is turned back to front and the natural feel of the physics is replaced by something, that though mathematically grounded and predictable, bizarre. After completing the levels with reverse gravity you loop back to the start again except this time the walls are only visible when you have your shield active. Finally after completing this set you face the levels a final time with the both the gravity reversed and the walls invisible.
Deep in level 5Thrusts sound effects are simple with only the occasional beep of a gun or engine sound. Its graphics are simple vector based shapes but are full of character and have a timeless look that has allowed them to age gracefully. The background of each cavern is made up of a series of striped horizontal lines which I suspect was done this way for performance reasons.
Nowadays it seems every game on the shelf features physical simulation to one degree or another. Cars behave realistically, objects tumble and fall, and puzzles in a game can be hinged on "real life" physical properties such as those found in Half Life 2. However in many games the physics feels bolted on for no particular reason other than that it can be done. Thrust doesn't fall into this trap and for me remains one of the superior examples of how physics and gameplay can be intertwined.
After working on Thrust Jeremy Smith collaborated with Peter Irvin on another BBC classic Exile before moving on to work on the Amiga. Exile also had a realistic physical model and in many ways paved the way for the physics puzzle based games mentioed earlier. Sadly he passed away in the 1990s. | 
