Syntax is a four-way scrolling shooter in which you have to save the day by finding ten deactivation crystals to drop into the baddies' ventilation shafts. There are various ground features which, if flown over, will produce desirable effects. The action is viewed from overhead, Uridium-style.
That's the theory anyway - in practice things are rather different. To tell the truth, this is quite possibly the worst game I have ever played. Apart from Transylvanian Tower perhaps, but that was in a different league altogether. The scrolling is jerky, your 'impulse drive fighter' is nauseatingly unmanoeuvrable, there are only two different sound effects (a beep and a slightly higher beep) and even the Sinclair character set makes a special guest appearance. Other problems include dodgy collision detection, primitive graphics, cursor-key controls... I could go on for hours. The fact is it's practically impossible to tell what you can fly over and what you can't.
Dreadful. Quite dreadful.