The 3D models the Doom engine can support are definitely no Half-Life 2 or Doom 3, it probably can't even support Ocarina of Time quality models. You, of course, would need much better engines for good 3D models. But the engine was made in 1992 or sometime around that, so it's forgivable. And for what this engine I guess supports, that is high quality for the engine, even though today's games could give way better models. Maybe you could make a better quality Link model, take pics of the animation frames, then make it a sprite so it can look way better, software players can use it, and still make it easy for the engine to support, since it's actually sprites of the model, not the model itself. How about you do that?