Portal Defense Unblocked: Play Free Online

How to play Portal Defense

Portal Defense is an Aizi Original tower defense game. Space monsters pour out of rifts and march along a glowing path toward the portal, with Aizi standing guard beside it. If you are looking for Portal Defense unblocked, it plays right here in your browser with no download and no account.

You place towers on the pads beside the path. When you press Start, a wave of monsters sets off and your towers fire on their own. Every monster that reaches the portal takes away some of its 20 health, and bigger monsters hit harder. Clear all 20 waves of a map to win it, and the next map unlocks.

Before each wave a card tells you exactly what is coming, for example “Next: 12 Swarmlets + 2 Healers”. That gives you time to build the right defence instead of guessing. You can also call a wave early for bonus stardust once you feel confident.

1. Read the wave card
2. Build or upgrade towers
3. Press Start, or call the wave early
4. Towers fire on their own

Controls

Action	Keyboard	Mouse / touch
Pick a tower	1 to 5	Tap it in the tray
Build	Not needed	Tap a glowing pad (tap again to confirm on touch)
Upgrade / sell	U / S	Tap the tower, then the button
Change target (first, strongest, closest)	T	Target button
Start or call the next wave	Space	Start button
Speed 1x / 2x	F	Speed button
Pause	P	Pause button
Monster guide	G	Book button

The five towers

• Laser Turret: fast single-target shots that also hit flying monsters. Its last upgrade adds a twin beam.
• Freeze Beacon: slows everything in range and reveals invisible Stealth Phantoms. Fully upgraded, it freezes the whole area for a moment every few seconds.
• Comet Mortar: slow, heavy splash damage against ground monsters, with cluster bomblets at the top level.
• Tesla Coil: chain lightning that jumps between 3, then 5, then 7 targets. Great against swarms.
• Gravity Well: drops a singularity that drags monsters back along the path and burns them while they struggle.

Each tower has two upgrades, and every upgrade changes how it looks, so you can read your defence at a glance. Selling returns 70% of what you spent.

Know your monsters

There are ten monster types, and each has a weakness. Here are six to watch for:

Monster	Weakness
Rock Grunts	Shrug off small hits, so meet them with the Mortar.
Shield Bearers	Block beams from every side except straight behind, but the Mortar and Tesla ignore their shields.
Speedsters	Need a Freeze Beacon.
Void Flyers	Float over comets and wells, so only lasers and lightning reach them.
Splitters	Burst into three smaller monsters when they die.
Healers	Patch up everything around them.

The first time you meet a monster it is added to the Monster guide, which lists its weaknesses.

Tips to get better

• Build a mix early. One tower type rarely holds a whole map. A Laser plus a Freeze Beacon is a strong start.
• Put slows before damage. A Freeze Beacon at the start of a long straight makes every tower after it hit more often.
• Read the wave card. If flyers are coming, make sure lasers or a Tesla Coil cover the path.
• Keep a beacon near the portal. Stealth Phantoms cannot be targeted until something reveals them.
• Upgrade before you spread out. A level 3 tower usually beats two level 1 towers.
• Save stardust for wave 10. The Rift Titan arrives with huge health and armour, so it pays to be ready.

Aizi's tip on the fork map, check both lanes before every wave. The path splits, and monsters do not always pick the side you expect.

The maps

Portal Defense has four maps that unlock in order:

1. Spiral OrbitA gentle single lane that coils into the portal.
2. Fork NebulaThe path splits in two.
3. Asteroid RunA long zig-zag through drifting rocks.
4. Twin RiftsAn expert map with two entrances on opposite sides.

Similar games on Aizi

Want more challenge? Try Geometry Vibes or Red Hardcore Platformer, or plan your moves in Color Roll 3D. You will find them all in the Skill dimension.

Questions players ask

How do you play Portal Defense?

Build towers on the glowing pads next to the path, then press Start. Monsters walk the path toward the portal, and your towers fire at them automatically. Earn stardust from every kill and every cleared wave, and spend it on more towers and upgrades.

How many towers and monsters are there?

Five towers, each with two upgrades, and ten monster types, from fast Blob Scouts to the Rift Titan boss on waves 10 and 20.

How do I get three stars?

The portal starts with 20 health. Finish all 20 waves with 17 or more left for three stars, or 9 or more for two.

Can I play Portal Defense on my phone?

Yes. On a phone the map turns to fill the screen. Tap a pad, pick a tower from the tray and tap again to confirm.

Does Portal Defense save my progress?

Yes. Your stars, unlocked maps and the monsters you have met are saved in your browser.