It’s 2d GTA but set in an awesome pseudo-noir retro-futuristic environment with very cool-looking cars. Of course you wouldn’t know this by looking at the extremely average-looking taxi on the box art which looks nothing like the taxis in the game.
From Wikipedia :
The time period the game is set in is not specified – conflicting sources suggest anything from “three weeks into the future”, to the year being 2013, despite in-game references to the “new millennium” that is coming (implying the game takes place around its time of release, in 1999).