SCI - Special Criminal Investigations - is the sequel to Chase HQ, you won't be surprised to hear, because it's practically the same game! Oh yes, there are a few additions and variations, but nothing that will make you dampen your diaper with excitement.
It's a 128K only game, and the plot's pretty familiar - you're a special agent chasing hoodlums through suburbs, cities and deserts in your souped-up sports car. At the start of each level you receive your assignment from your gorgeous controller (ooh, I do like a woman in uniform). Your first task is to rescue three kidnapped girls, chasing their abductors along dual carriageways, freeways and desert roads.
Your car has automatic gears, so all you have to worry about is burning up the tarmac at full pelt, screeching around the curves and up and down the bumps and dips, ploughing through the sand and avoiding obstacles which slow you down. No matter how many cars, motorbikes, bollards, buildings and fences you bash into, you don't get damaged; you do, however, lose speed, which is crucial, because you lose a life if you don't catch up with your target before the timer runs out. Fortunately you can resume play from the current position if you have credits left.
Your position relative to your target is shown on a radar scanner on the right hand side of the screen. Once your target is in view, an arrow indicates him, and you get to poke your head out of your sunroof (presumably steering the car with your... er, feet) and bang away at the baddies with your handgun. A crosshair appears to tell you when you're lined up with him, and when you force him off the road you get a graphic screen showing your subtle interrogation of the suspect (bang... smash... take that... yarooo.. gosh...)
On later levels, the action gets faster, the road twists and turns more violently, and extra weapons can be picked up as they are dropped by a helicopter thoughtfully sent out from your base. The first weapon is a rocket launcher, which gives you six super projectiles to shoot off. The baddies get heavy artillery too, though, and you also have to cope with hazards like trucks unloading cargo over the road.
The original SCI coin-op features gorgeous graphics and super sound, while the sound in the Spectrum version is nothing but an irritation - I think the in-game music is meant to sound like the theme from Miami Vice, but it's more like the grinding of a dentist's drill. The whining of the engine and popping of your gun don't add much to the excitement, either.
Now, I don't want to sound too unenthusiastic about SCI - it's a pretty good game, with lots of excitement and decent graphics and animation. Trouble is, it just doesn't add enough to Chase HQ, and since that was a chart success and has also appeared in various compilations, you may well have it already. If so, I'd suggest you save your dosh for something a bit different rather than retreading old ground with SCI.