Murkon's Vengeance is a browser based first person dungeon crawler by Samuel Stoddard published in 2005. Similarly to Wizardry IV: The Return of Werdna, it takes place in the same dungeon as the first game, but inverting the roles, you know play as the evil Murkon, the final boss of Murkon's Refuge, and your goal is to defeat the adventurers that are invading your dungeon. To help you in your mission all the dungeon dwelling monsters are on your side, but the adventurers have powerful equipment, spells and stats, while your minions have few hitpoints and can't benefit from many of the magical items scattered around the dungeon, as monsters rarely can in Dungeon Crawlers - despite your overwhelming numbers, the odds are stacked against you. The 200 adventurer parties you will face in the game are all actual player parties converted from Murkon's Refuge.
Murkon's Vengeance is available in Rinkwork's The Role-Player's Vault along with Murkon's Refuge.