Outbreak Containment Lost

Outbreak: Containment Lost — A Progressive Infection-Survival Experience

Containment has failed. The outbreak has begun.

Outbreak: Containment Lost is a large-scale infection-survival modpack for Minecraft Forge 1.20.1, built around a slowly escalating apocalypse rather than an immediate, endless swarm.

The opening days provide a brief opportunity to gather supplies, establish shelter, and prepare. The infection begins appearing early in the world’s life and continues growing across approximately 100 in-game days, becoming more widespread and dangerous as time passes.

Ordinary hostile mobs are less common, allowing the infected to become the world’s primary threat. Wildlife still inhabits the wilderness, abandoned structures hide valuable equipment, and every journey beyond the safety of your shelter carries genuine risk.

This is more than a zombie modpack. It is a long-term survival experience focused on preparation, exploration, progression, and enduring the gradual collapse of containment.

Early Beta — Active Development

Outbreak: Containment Lost is currently in early beta and is not a finished or fully stable modpack. The current 0.4.0 release establishes the foundation of the intended experience, but bugs, balancing issues, performance problems, incomplete quests, unfinished progression, and major changes should still be expected.

Future updates may require a new world. Always back up important saves before updating.

Quests, recipes, progression paths, structures, loot, infection balancing, and long-term outbreak systems will continue to be developed and refined as the pack moves toward a full release.

The infection is a slow burn—not an instant wall of enemies.

• Early encounters begin smaller, giving you time to understand the threat and prepare.

• Infected activity escalates across approximately 100 in-game days and continues developing beyond the opening stages.

• Larger groups and increasingly dangerous threats become more common as the world grows older.

• Infection-related enemies serve as the world’s primary hostile threat.

• Vanilla zombies, skeletons, creepers, and other ordinary hostile mobs remain enabled but appear less frequently.

• No artificial infected-population cap is imposed by the modpack.

• Natural spawning, conversion, evolution, progression, and intended horde behavior remain active.

Improved environmental ambience, footsteps, weather, reverb, directional sound, and firearm audio make nearby threats easier to hear—but not always easier to locate.

Survive with whatever you can find.

Early survival begins with basic tools, bows, shields, medieval weapons, food, clean water, and whatever shelter you can build or recover.

As the infection intensifies, firearms, ammunition, attachments, armor, and tactical equipment become increasingly valuable. Powerful gear can make survival easier, but obtaining it often means entering abandoned structures, military locations, and infected territory.

Long-term survival requires more than combat:

• Manage thirst, temperature, localized health, injuries, food, and environmental dangers.

• Prepare meals, establish farms, treat water, and build dependable resource supplies.

• Use improved melee combat, first-person animations, crawling, and tactical movement.

• Follow quest-driven survival, exploration, containment, and recovery objectives as they continue to develop.

Your Objective

Survive the infection. Secure your shelter. Find food and clean water. Explore the ruins. Recover better equipment. Prepare for escalation. Contain what remains.

The best supplies are rarely found somewhere safe.

The world is filled with abandoned and dangerous locations containing food, weapons, ammunition, equipment, and clues about what happened.

Explore ruined settlements, aviation sites, watchtowers, radio towers, industrial facilities, military locations, underground structures, camps, bunkers, and emergency shelters.

Entering an unfamiliar location without enough ammunition, food, medical supplies, or a reliable escape route can quickly become fatal. Exploration rewards preparation, but every valuable location carries risk.

World generation is configured to provide more varied continents, mountains, forests, rivers, caves, and wilderness while reducing excessively repetitive biome stretches, oversized oceans, extreme frozen regions, and unnecessary structure overlap.

Wildlife & Environment

The wilderness remains alive even as civilization collapses. Bears, seals, crocodiles, caimans, turtles, whales, birds, large cats, aquatic creatures, and other recognizable wildlife inhabit the world. Many fantasy and dimension-based creatures have been removed to better support the pack’s grounded apocalypse setting.

Seasons, weather, temperature, and environmental conditions affect every expedition. Travelling without suitable clothing, supplies, or shelter can be just as dangerous as the infected.

A temporary shelter will not carry you through the entire outbreak.

Develop farms, food supplies, storage, machinery, engineering systems, and dependable defenses capable of supporting long-term survival.

• Expand beyond scavenged supplies by producing essential resources at home.

• Build mechanical and industrial systems that support larger, more capable bases.

• Improve storage, food production, water access, lighting, and equipment preparation.

• Customize your shelter with expanded building materials, furniture, decoration, and survival-base equipment.

• Reinforce your position as infected activity and horde sizes increase.

Your base must eventually become more than somewhere to hide—it must become a location capable of keeping you alive as the world becomes increasingly hostile.

Darkness makes every journey harder to read.

Nights are intentionally dark and heavily dependent on available light. Torches, lanterns, flashlights, and other portable light sources are essential when travelling after sunset or exploring underground.

Environmental effects, weather, foliage, animations, and darker nighttime lighting strengthen the atmosphere without unnecessarily obscuring daytime exploration.

Shader support is included for players who want a darker and more atmospheric visual experience. Results and performance will vary depending on the selected shader, graphics settings, resolution, render distance, and hardware.

If shaders are too demanding, disable them or use a lighter preset before reducing the settings that affect gameplay visibility.

Large hordes without solving performance by removing the horde.

Large infected groups can place significant strain on Minecraft, so the pack includes carefully selected performance mods, tuned configurations, and custom compatibility work.

Outbreak EPCA Performance Compatibility reduces unnecessary infected-AI calculations involving target searches, light-source checks, group behavior, and shared pathfinding without reducing the intended infected population.

The optimization does not change infection progression, natural spawning, conversion, evolution, health, damage, attacks, or active combat behavior. Its purpose is to preserve large-horde gameplay while improving client and server performance.

Additional rendering, memory, entity, chunk-loading, particle, animation, lighting, and audio optimizations are included throughout the pack.

Outbreak: Containment Lost remains a large modpack. Actual performance will vary based on CPU, GPU, allocated memory, render distance, simulation distance, shaders, world generation, and the number of active entities.

Built for Minecraft Forge 1.20.1.

• Minecraft: Java Edition 1.20.1

• Mod loader: Forge 47.x

• Java: 17

• Project type: Infection-survival modpack

• Current release: 0.4.0

• Development stage: Early Beta / Active Development

Use matching versions of the modpack on the client and server. Changing included mods or replacing the supplied configurations may alter infection progression, quests, balance, world generation, performance, or stability.

Most major world-generation changes affect new worlds or newly generated chunks. Existing terrain will generally remain unchanged, and some future beta updates may require starting a new world.

All mods, resource packs, shader packs, libraries, and tools included in the modpack remain the property of their respective creators. Refer to the project’s dependency and credit listings for the complete collection.

Join the WITHHELD STUDIOS community.

Get help, report problems, share performance results, suggest improvements, or post screenshots through the official Discord:

Discord: https://discord.gg/zFrNaBAMbx

When requesting support, please include:

• Your Outbreak: Containment Lost version.

• Your Minecraft and Forge versions.

• Whether you are playing in singleplayer or on a dedicated server.

• Your CPU, GPU, total system RAM, and allocated RAM when reporting performance problems.

• A clear explanation of what happened and how to reproduce it.

• Your latest.log and server log when relevant.

• Your crash report, if one was generated.

Outbreak: Containment Lost is created and maintained by WITHHELD STUDIOS.

Thank you to everyone who tests the beta, reports problems, shares feedback, and helps shape the outbreak as development continues.