However, the ammo bonuses are increased and the weapon switching is faster. Enemies are more relentless, unpredictable, faster, and agile. As opposed to exactly copying the difficulties of other Doom 64 ports, it is now an experience focused on brutal action. The “Be Merciless!” difficulty setting combines parts of the “Nightmare!” mode introduced in Doom 64 RE with the 'Hardcore!' mode of Doom 64 EX and other tweaks. Current Differences from Doom 64 RE and Original Doom 64 'Be Merciless!' Difficulty This branch is primarily hardware focused, however emulation compatibility is still a goal. Where Doom 64 RE is a complete reverse engineering of Doom 64 by Erick194, which has provided the pathway to achieve such modifications.
Merciless Edition is a fork of Doom 64 RE where new features for Doom 64 are implemented with the goal of maintaining Nintendo 64 hardware and vanilla gameplay compatibility.