what on earth is a .4ds file? 3ds max is having none of it in the event its a misnamed .3ds file, blender is having none of it on the .3ds imported. I guess it could be cinema 4d but those are .c4d not .4ds
The 4DS file extension is associated with 4D and used for files that hold database Windows data segments. No Idea if that will help you.
.4ds is a file type made specifically for mafia, and there is very few ways to open it, i know about 2, both a extremely old plugin to Blender, latest version of blender i can use it in is 2.49, and the other way is to open that kinda file is ZModeleR 1, with the later versions having the .4ds filter removed. It is a archaid file type that is no longer under use.
Getting the stock T3D soldier to work in FPS in Beam has been on my mind lately. Would be seriously cool to walk or hike some of these awesome maps.