TIE Fighter: Total Conversion is a mod for X-Wing Alliance, the 1999 semi-sequel to TIE Fighter featuring a much better engine. The mod is a spinoff of the X-Wing Alliance Upgrade mod, which replaces all of the game's models and textures with much more modern equivalents whilst retaining the classic gameplay.
The game revamps all 13 campaigns from the original game and its two expansions, for a total of 104 missions. The game also features 41 "reimagined" missions, with many more ships (including the Super Star Destroyer Executor in some cases) added to the original missions to dramatically increase the size and scope of the battles. The mod also, impressively, supports VR.
To play the game, you'll need a copy of X-Wing: Alliance from GoG, a download and install of the X-Wing Alliance Upgrade mod, and a download and install of the TIE Fighter: Total Conversion mod, all of which are fairly self-explanatory.