On i386 and beyond (assuming MS-DOS as the target OS and IBM PC as the target platform), my impression is game developers most typically used Watcom C / DJGPP plus one of the DOS extenders (DOS4GW, cwsdpmi etc.) plus graphics libraries such as SVGAKit or Allegro.
I wonder what were the most used toolchains (compiler, runtime if any, libraries) for the i286 era? In particular, did games typically use the 16-bit protected mode, and if so, was there something like a "16-bit DOS extender"? Or, rather, was using EMS / XMS sufficient?
I recall Borland had DPMI16BI.OVL, but it's a question if Borland was the compiler vendor of choice for game developers back in the day, and even if it was, whether the game developers used the Borland's DPMI?