Doom2X-treme (also called Doom 2 Extreme) is the second released total conversion made by Chuck Lai. It is a follow up to Doom2X and Ultra Doom2X. While Ultra Doom2X focused on all new gameplay with the original Doom 2 levels, Doom2X-treme focuses on these weapon and enemy enhancements in "Best Of" series of 32 levels created by other designers.
Doom2X-treme gives larger pool of HP for both monsters and player, while boosting weapons to a whole new level. All weapons fire faster, and contain more damage. This caused a rebalance in the gameplay, speeding up the action piling up the body count.
An evil being known as Comtar takes the remains of the Icon of Sin and resurrects his evil plan for the domination of Earth.
All the cheat codes were changed in the original version of Doom2X-treme.
In the final level, map 30. The teleporter leading to the final battle will only work on Ultra Violence difficulty, playing the map at any other difficulty will cause nothing to happen, getting the player stuck. Also in the original version of the Doom2X-treme the Cyberdemon's Railgun Projectiles would bypass God Mode allowing for the player to still be severely injured or killed in one shot, while this was indeed a "bug", it was kept in so cheaters still had to find a way to survive on their own Boss Fights. Frontend programs that run Doom 2 like GZDoom or Doomsday no longer contain the Cyberdemon's Railgun Projectile bug.
Doom 2 Extreme was followed by Doom 2 Extreme Gold.