I have 2 suggestions...
There is the excellent Quake 2 to Delphi project ( http://www.sf.net/projects/quake2delphi/. I think you will be well on the way to your first person shooter if you used this as your starting point. The team is in the process of porting the rendering DLLs so it won't be long before the whole thing written Delphi .

Another suggestion, which may require more work is DeathTruckTion ( an old home page can be found @ http://deathtrucktion.online.fr/ though the latest source is part of http://www.sf.net/projects/jedi-sdl ) which is a 3D engine demo that is part of the JEDI-SDL project. The engine currently uses Pick-up trucks tthat can be driven in a death match arena, but could easily be modified for a first person shooter. All the main engine code is Delphi/Kylix and uses OpenGL for 3D acceleration and should work on both Windows and Linux.


I hope this helps.