Between when I joined dma-design in 1995 and 1999 there were several titles in development.
Gta & gta2
Body Harvest for the N64
Space Station Silicon Valley for the N64
Covert which became Wild Metal Country
Attack which was canceled
Clanwars which was canceled
In 1999 the company went through a series of changes. It had been sold to Gremlin earlier. Gremlin sold dma-design to BMG. BMG sold dma-design to Take2-Interactive. Take2 set up the label 'Rockstar Games' and place dma-design underneath it.
Dma-design (based in Dundee, Scotland) opened a satellite studio in Edinburgh.
Members of two teams that had just finished their games (Body Harvest and Silicon Valley) were given the option to move to Edinburgh. The majority went.
Months later the main office in Dundee was closed altogether.
At this point there were 2 teams sitting in Edinburgh but no projects to work on. There wasn't much in terms of direction from Rockstar New York so everybody started working on their own pet projects.
I myself worked on a racing game with spheres for a bit.Leslie Benzies and Aaron Garbut worked on a Godzilla game. (There were rumours that David Jones could get the rights to it) while we were still in Dundee. Then they thought it made sense to start working on a new gta game. The idea was to simply take gta into 3D. They continued this after the move to Edinburgh. The idea seemed a winner and most of the old Silicon Valley team (including me) joined them.
The members of the other team (Body Harvest) came up with their own game idea which ended up being Manhunt.
There briefly was another gta offshoot being developed by the original gta team. The game was internally known as gta2.5. It was 2.5 for two reasons:
It came after gta 2.
The perspective was 2.5 dimensional. This is what developers call isometric. It is basically the 'Sim City' perspective. It is more 3d than the old top down but not quite full 3d.
gta2.5 was set in Miami. I've never seen it run as it died when the Dundee office was closed.