Zero Tolerance (gameplay mod)

Zero Tolerance is a gameplay mod for the ZDoom and GZDoom source ports. It was created by by Setzer (aka Zero Prophet) and originally unveiled in 2007, with a final release on 29 May 2008. In the mod, the player takes the role of a rogue cyborg, slated for termination, that has been reactivated as a last ditch effort to repulse a demonic invasion. It contains eleven new weapons, and was notable at the time for its advanced visual effects, the inclusion of reloading, and the great divergence from the original game. Its cyborg theme has led to comparisons with Xaser's Zen Dynamics, which is cited as an influence.

The mod has proven enduringly popular over the years, and maintains a high rating on the /idgames archive. On February 2016, Mikk- released an update for the mod dubbed Zero Tolerance Upgrade, reworking some of the features to have better compatibility with modern versions of GZDoom, as well as rebalancing certain aspects of the mod.

Gameplay
Zero Tolerance completely replaces the vanilla arsenal, while also modifying several other aspects of the game including some of the enemies and the player's appearance. Below is a list of the weapons included:
 * Flare gun: replacing the melee fist, this weapon launches fireballs with infinite ammo, albeit needing to reload after each shot. What makes this weapon peculiar is that it can be upgraded up to nine times if the player finds the necessary upgrade kit (which replaces the berserk pack). Said upgrades grant it higher projectile velocity, increased damage, and other improvements.
 * Mixom-125 overdriven 'Beavertooth' chainsaw: the replacement for the chainsaw, it has two different attack modes as it can also be swung alongside the standard attack type.
 * 'Prophet' high-caliber handgun: Equipped with a laser pointer, this rapid-fire pistol can also be dual-wielded should you find another one. It has a clip capacity of eight.
 * 'Susan' Mark II photon pistol: This energy based weapon fires four small explosive projectiles in quick succession, utilizing radioactive storage units as ammunition. It has a clip capacity of ten and replaces the shotgun.
 * 'Raiden' military-issue assault rifle: The equivalent of the chaingun, this assault rifle fires high-damaging rounds and has a clip capacity of 30.
 * 'Atlas' ultra-velocity flak cannon: Replacing the super shotgun, the atlas flak cannon fires eight pieces of fast-moving and bouncing flak that deal massive damage to enemies. It has a clip capacity of five.
 * 'Xanadu' experimental liquid crystal pulse rifle: This powerful gun replaces the plasma rifle and rapidly fires bouncing plasma projectiles that can quickly swarm groups of enemies. It has a clip capacity of 40.
 * 'Bouncer' .50-cal HighVel machine gun: An even beefier assault rifle, it has a moderate firing speed but high damage output, and a clip capacity of 50.
 * 'Prometheus' alpha-model radioactive blaster: This devastating plasma-based weapon fires a swirling fireball that deals devastating damage against any target, and the resulting shockwave lingers on for a time continuing to damage whatever it has hit. It has a clip capacity of 9, but each shot takes up 3 ammo.
 * 'Genova' protoype cluster ejection grenade launcher: This grenade launcher, replacing the rocket launcher, can quickly fire powerful explosive shells that upon contact release further droplets that also explode and damage anything nearby. It has a magazine capacity of six.
 * Dual prototype 'Zero & Infinity' Vortec disruptors: The most powerful weapon in the mod by far, it has two different attacks, being able to either shoot a white stream that can hit multiple foes, or generate a black hole devastating anything in its radius for a time.