Undead Invasion

Undead Invasion: Build Defenses and Survive Endless Zombie Waves

Undead Invasion is a side-scrolling zombie survival game that combines shooting, melee combat, defensive construction, and roguelike progression. You defend your position through a sequence of increasingly dangerous days, earning money from completed waves and spending it on weapons, training, healing items, armor, barricades, and traps. Death ends the current run and removes its progress, so every purchase and defensive decision affects how long you survive.

The game is not only about eliminating zombies quickly. Ammunition must be managed, weapons need to be reloaded, and defensive structures must create enough time for you to respond when several enemies arrive together. As the days advance, the undead become more numerous and harder to contain.

How Undead Invasion Works

A run is divided into days. Early encounters introduce basic movement, shooting, melee attacks, and kicking, while later waves increase the number and strength of the approaching zombies. Completing a day rewards you with money and opens a preparation phase before the next attack.

During preparation, you can select equipment and purchase a limited number of improvements. Available options include training upgrades, support items, firearms, melee weapons, armor, roadblocks, and other defensive tools. Choosing only high-damage weapons may leave the base exposed, while spending too much on barriers can limit your ability to eliminate stronger enemies.

The run continues until the survivor is defeated. A results screen then summarizes information such as the number of days completed, total kills, income, and developed statistics. You must begin again afterward, making each new attempt an opportunity to apply a different spending or defense strategy.

How to Play Undead Invasion

1. Prepare your loadout. Select available firearms, a melee option, useful items, and protective equipment before starting the next day.
2. Place defensive structures. Use roadblocks, barricades, or damage traps to delay enemies before they reach your position.
3. Begin the wave. Start the next day when your weapons and defenses are ready.
4. Attack from a safe distance. Use firearms while zombies are still separated and easier to control.
5. Reload before enemies surround you. Create space or move behind a defensive layer instead of waiting until the magazine is empty at close range.
6. Use melee attacks and kicks in emergencies. Push back or strike enemies that break through your ranged defense.
7. Activate items when they provide clear value. Save healing supplies, bombs, and other limited tools for situations that threaten the run.
8. Complete the day and collect your reward. Spend the earned money on improvements that address the weaknesses revealed by the previous wave.

Undead Invasion Controls

• W, A, S, D: Move the survivor.
• Left or Right Mouse Button: Fire the equipped weapon.
• R: Reload.
• Q: Switch weapons.
• E: Perform a melee attack.
• 1–9: Use the item assigned to the selected slot.
• Spacebar: Kick a nearby zombie.
• Tab: Start the next wave.
• Esc: Open the pause menu.

These controls allow you to move, shoot, change equipment, use close-range attacks, activate items, and control when the next wave begins.

Build a Defense That Creates Time

Barricades and traps are most useful when they slow or damage zombies before those enemies reach the survivor. Placing every structure in one location can create a strong first barrier, but it also leaves no backup layer if that position collapses.

A layered layout is usually more flexible. Place an initial obstacle where it can delay the first enemies, then keep another defensive point closer to your firing position. The gap between these layers gives you room to reload, switch weapons, or eliminate zombies that become separated from the group.

Damage traps such as spike barriers and Claymore mines are better used where several enemies are likely to pass. Roadblocks and barricades primarily delay movement, giving firearms more time to work. The available equipment includes blockers, damage traps, and additional defensive utilities.

Choosing Weapons for Different Situations

Undead Invasion includes several firearm categories, including rifles, assault rifles, shotguns, sniper weapons, machine guns, and heavy weapons such as the minigun. Melee choices include bats, axes, hammers, bladed weapons, and a chainsaw.

Equipment Type	Best Use
Fast-firing guns	Control groups of ordinary zombies and respond quickly when several targets approach.
Shotguns	Deliver strong close-range damage when enemies reach a barricade or crowd together.
Precision weapons	Damage dangerous targets before they reach your main defensive position.
Heavy weapons	Handle dense late-wave pressure when lighter firearms cannot clear enemies quickly enough.
Melee weapons	Provide a backup attack when zombies are too close or when conserving ammunition matters.

Carry options that cover more than one combat distance. A strong long-range weapon may perform well while the barriers remain intact, but a shotgun or melee tool can become more useful after zombies break through.

How to Spend Money Between Days

The shop may offer training for speed, strength, or kicking, along with healing supplies, weapons, armor, and defensive items. You can buy only a limited number of items during the preparation phase, so the most expensive option is not automatically the best choice.

Review what caused difficulty during the previous wave. Improve damage when zombies survive for too long, buy a stronger barrier when the line collapses early, or invest in healing and armor when occasional hits are ending otherwise successful runs.

Do not save all available money while using equipment that can no longer handle the current day. Currency has value only when it improves your chance of surviving long enough to earn the next reward.

Defense Mode and Playground Mode

Defense Mode

Defense Mode contains the main survival progression. Zombie waves intensify over time, resources are limited, and death ends the run. This mode tests how well you can combine combat, purchasing decisions, loadout preparation, and defensive placement.

Playground Mode

Playground Mode provides a lower-pressure environment for testing weapons, traps, and defensive layouts. It is useful for learning the range of a weapon, checking how structures interact, or comparing several strategies without risking a developed survival run.

Useful Undead Invasion Strategies

• Build before the battlefield becomes crowded. Place defenses during preparation so you are not searching through building options while zombies are already attacking.
• Reload behind a barrier. Defensive structures are valuable because they create the time needed to refill a weapon safely.
• Use kicks to restore distance. When one zombie reaches you, pushing it back can create enough room to shoot or switch equipment.
• Save explosives for groups. A bomb or area-damage trap provides more value against a cluster than against one ordinary enemy.
• Keep a close-range backup. A shotgun or melee weapon can prevent a breach from immediately ending the run.
• Spread defenses across multiple layers. A second obstacle gives you somewhere to retreat when the outer barrier fails.
• Upgrade according to the last failure. Let the previous day reveal whether your main weakness is damage, health, ammunition, movement, or defense durability.

Common Mistakes to Avoid

Standing Still While the Horde Advances

Remaining in one exposed position allows several enemies to close the distance together. Move within the defended area and preserve enough space to reload or change weapons.

Using Every Limited Item Early

Healing supplies and explosives may be unnecessary during the first easy encounters. Saving them for a crowded or dangerous wave gives them more strategic value.

Depending on One Weapon

A weapon suited to distant enemies may perform poorly after the barricades break. Prepare another option for close combat instead of assuming one firearm can solve every situation.

Starting the Wave Before Preparing

Tab begins the next attack. Check your ammunition, selected items, equipment, and defensive placement before using it.

Ignoring Playground Mode

Testing unfamiliar traps and weapons during a serious run can waste money or expose a weak setup. Use Playground Mode to understand new equipment before depending on it.

Frequently Asked Questions

What is the main objective in Undead Invasion?

The objective is to defend your position against increasingly difficult zombie waves and survive as many days as possible.

What happens when the survivor dies?

The current run ends and its progress is lost, requiring you to begin again from the opening day.

How do you earn money?

Money is awarded for defeating zombies and completing days. It can be spent during preparation before another wave.

What can you purchase?

You can obtain firearms, melee weapons, training upgrades, health items, armor, barricades, traps, and other defensive equipment.

Who developed Undead Invasion?

Undead Invasion was developed and published by ZapGames and was released on December 10, 2025.

Hold the Defense for One More Day

Undead Invasion makes each wave a test of both combat skill and preparation. Shooting keeps the undead away temporarily, but defenses, equipment selection, resource spending, and emergency melee attacks determine whether your run can continue.

Build layered barriers, reload before the horde reaches you, and spend each reward on the problem most likely to end the next day. The farther you progress in Undead Invasion, the more important it becomes to treat every weapon, item, and defensive structure as part of one survival plan.