The golden rule of video game sequels is to offer more of the same, but bigger and better. Give 'em beefier guns, screen-filling bosses and a multi-player mode - but don't go alienating the fans with risks. As sequels go, Jak 2 stopped just short of punching its fans in the face.
Developers Naughty Dog boldly ditched the first game's colourful, Mario 64-style, platform action, in favour of a gritty, gun-wielding, free-roaming, open world - like setting In the Night Garden on the prison planet from Alien 3. The critics were split - but history suggests the gamble paid off.
Jak 2 begins in familiar territory as the duo test a mysterious device they found in the first game. But at the press of a switch our heroes are plunged into a time rift, hurtling them into another world. It's a terrific opening that wrong foots the player before flooring them with an audacious rug puller of a plot twist.
The heroes find themselves in a strangely brutal new world. Jak is immediately kidnapped and it isn't until two years and several painful experiments later that Daxter finally manages to rescue him.
You're plunged into darker territory. Jak looks meaner (must be those long years of torture) and is no longer the cheerfully monosyllabic hero of old - his first utterance being a violent oath of revenge. Even Daxter, the series' comic relief, bandies about mild swearwords like an unruly toddler. All this and the game has barely even begun.
CITY OF DREAMS
Once it does start the difference is breathtakingly apparent. Cracked streets lined with tumble down houses stretch off into the distance. Colourful citizens amble from place to place. Extraordinary hovering vehicles jostle in the air. Most striking of all, a small circular map at the bottom of the screen reveals just how much things have changed.
Immediately the game feels more like a Rockstar game than a cutesy platformer. It doesn't take long before you realise that this is a different breed of adventure - an altogether more ambitious breed of sequel.
You're encouraged to explore, make contacts and perform missions right away. Haven city is huge (its several different districts include slums, an affluent centre, a bazaar, a bustling port and beautiful gardens) and getting around is made easier by jacking vehicles and taking them for a spin.
What's immediately impressive is just how seamless the world is. Jak can dart from street to sewer access tunnel to Precursor temple with barely a pause for breath, never mind a loading screen.
Barrelling along, by way of some traditional platforming, racing, escort and collection missions, you're introduced to several other features that set Jak 2 apart. In the first few hours guns are added to Jak's arsenal. Later, a hover board. The missions that follow are thrillingly diverse, challenging you to score big on the shooting range, topple high scores at a skate park, take part in a racing championship and battle your way through increasingly difficult platform challenges and boss battles. Jak 2 didn't just draw on GTA3 for inspiration - it swallowed the entire PS2 back catalogue.
But if the wealth of things to do is staggering, the difficulty of the game is even more so. Death is around every corner on these dystopian streets. Simply stealing a vehicle, colliding with another driver or merely drawing your weapon alerts the attentions of the Crimson Guard (Jak 2's answer to Liberty City's finest), but shaking them off is far harder.
The missions themselves are just as unforgiving as enemies and traps whittle away your health before sending you way back to the start. Platform games are very rarely this hardcore.