I think people overestimate the value of 'portable' code. Even with C or other higher level languages you often have to code around platform specific problems or jump through hoops for platform specific optimizations. Regardless, if you understand what the code is doing then re-writing it for a different platform is pretty trivial, and isn't rewriting code the favorite sport of programmers anyway?
Granted it is not a modern-style piece of software, but look at David Murray's Attack of the PETSCII Robots: originally hand-written in 6502 assembly for the Commodore PET and since ported to something like 20 different platforms, many of which have wildly different video and audio hardware and several of which use a completely different processor.
Also compilers are hungry, wasteful, complex piece of codes fairly unsuited for 8 bits and 16 bits machines. DOS games started being written in C only when the 386 got commonplace.
Heck, even on 32 bits machines of the times (VAX), most things were written in pure assembly. That includes VMS.
Granted it is not a modern-style piece of software, but look at David Murray's Attack of the PETSCII Robots: originally hand-written in 6502 assembly for the Commodore PET and since ported to something like 20 different platforms, many of which have wildly different video and audio hardware and several of which use a completely different processor.