LOCK up your children — the first trailer showing gameplay from the forthcoming Grand Theft Auto V has been released.

Game trailers come and go, with most raising little more than a shrug of the shoulders from even the most avid joypad lovers.

But this is something else.

GTAV appears to be jaw-droppingly, unbelievably marvellous.

The trailer starts with an atmospheric sunset over a cityscape with jauntily angled palm trees in the foreground, while a blimp glides overhead.

The game is set in the fictional city of Los Santos, a subverted version of Los Angeles, first introduced in GTA San Andreas.

Even in that earlier game, in which Los Santos only made up about a third of the map (the rest being taken up by fictional versions of San Francisco and Las Vegas), it felt like a living, breathing city.

Playing it was almost as good as visiting Los Angeles — you could cruise through Hollywood (or Vinewood as it is called in the game) in an open-top sports car, pedal around the south central ghettos on a BMX listening to Dr Dre and randomly punch people working out on muscle beach.

What more could you want?

GTAV will undoubtedly offer more; it promises to be mind-bogglingly huge, encompassing a vast city with shops, mountains, freeways, malls and skyscrapers.

The trailer offers tantalising glimpses of some of the features on offer — sniping people through windows of distant tower blocks using a high-powered telescopic rifle, dangling from a helicopter on a wire, bank raids, knockout gas, wanton destruction.

But if you do get bored of machine gunning gangsters, it appears there will be plenty of other less violent offerings.

Cycling races, golf (there appears to be a mechanism more complex than many dedicated golf games of yesteryear), scuba diving, flying, parachute jumping — you name it.

Quite simply, this is going to be the most exciting thing to happen in gaming since . . . well, ever.

It looks so good that legendary games designer Hideo Kojima took to Twitter to say that he was ‘depressed’ after watching the trailer because his latest game, Metal Gear Solid V, won’t live up to it. And most tantalising of all — in the last few seconds of the trailer, a brief shot showing GTA online — something all GTA fans have been clamouring for for years. If this is as good as it looks, it will change your life.

Roll on September 17.