http://www.sim-garage.co.uk
3DSimEd is a visual tool allowing you to import data from many different formats including all Papyrus sims, rFactor, GTL, GTR, F1CC, Nascar SimRacing, Toca Race Driver and many other sim formats. A range of simple editing tools are available to allow you to modify data. Your models can then be saved to rFactor, GTL, N2003, GTR, and F1CC/F1-2002 formats. 3DSimEd also allows you to work with .3DS files giving a way for you to work with many 3D modelling applications. More details
TrkMaker allows you to create and edit tracks for various sim formats using a common database. The database describes the segments and surfaces that define the track. This data can then be exported to rFactor, GTR, Papyrus N2003, F1CC, or .3DS format. The initial database can be created from a GPL .TRK or N2003 .PTF giving you a way, for example, to start with a GPL track and build N2003 and other format tracks in a matter of hours
This may help you in your game attempt. it looks good for map conversions to GTL, too!