Science has yet to so much as hypothesise a limit to Doom modding (opens in new tab). There's Pirate Doom, Doom The Way Id Did, MSX Doom, Brutal Doom (opens in new tab), Donkey Kong Country Doom, and now GoldenEye 007 Doom. Modder demo_the_doomer has set about reworking the '97 N64 classic as a GZDoom (opens in new tab) mod.
The Dam level is apparently 75% done. In the long term, the mod's not aiming to be a perfect replica but a re-imagining of GoldenEye to play at Doom-like speeds (and include more Bond one-liners). There's a short demo (opens in new tab) available if you'd like to perform some recon.