04 Second front // Stronghold
A fortress core in an open arena fires on its own while Machines close in from every side. Pick one of five starting cores (Sentry, Arc, Mortar, Lance, and Incinerator), draft upgrades as the waves climb, and fire Repulse and Siege Shot yourself.
Relay Yard, wave 27: a surge charges from three gates, the Choke Point goes down, and a Siege Shot lands on 11 Machines.
Four levels, Core Perimeter, Foundry, Relay Yard, and Fragment Works, run 77 waves each, with their own armor trait, a signature enemy and a Mega Boss. Play on Relaxed, Standard, or Hard; earn medals that unlock Workshop perks; keep going in Endless after wave 77, or take on the Daily Defense, with Game Center leaderboards for both.
01 The arena
No route to build here: the core is the defense. Keep its shield up, decide where its firepower goes next, and step in when a swarm gets close.
Wave 1
Your fortress fires automatically. Protect its shield and core. Your weapons handle the firing. The shield protects your core until it falls.
Every side
Machines close in from every side of the arena. Machines that reach the shield wear it down; when it falls, the core is exposed.
Lasts 15 s · recharge 18 s
Tap Deploy Choke Point to deploy the triangles together. Machines in the marked gaps make weapon bars fill 50% faster. Drafts can turn it into the Conductive Choke Point and Reinforced Choke Point.
From wave 2 · Recharge 20 s
From wave 2, tap Repulse to push every Machine within 2.4 of the core back out by 1.3, damaging it and slowing it for 1.2 seconds. Bosses take the damage but hold their ground. It recharges over 20 seconds of combat. Remaining recharge carries into the next wave and pauses during drafts.
From wave 3 · Recharge 18 s
From wave 3, drag Siege Shot onto the field, or tap it and then the field. Aim at least 1.8 from the core. The shell lands 0.8 seconds later and blasts every Machine within 1.0. Land a boss inside the small center ring for a perfect hit: +25% Siege Shot damage. It recharges in 18 seconds and is ready at the start of every wave. Force Wave, Quick Repulse, Heavy Shells and Rapid Shelling can improve both weapons.
From wave 2 · Charge: 200 kills · Lasts 5 s
From wave 2, defeat 200 enemies to charge it. Tap when ready for five seconds of double recharge speed for Sentry, Arc, Mortar, Lance and Incinerator. Lance keeps its warning time. EMP keeps its normal cycle. No aiming required.
App Store preview · 0:17
Stronghold on iPhone: survive the chaos, hold the core, upgrade it between waves and break the Mega Boss on the final wave, 77.
Captured in-engine on iPhone, with caption bands. Music and sound effects from the game; no voiceover.
02 Starting cores
Your run starts with one weapon in the core. Each has an evolution that drafts can unlock, and drafts can install the others beside it.
Core 01
Fast tracking volleys. Kinetic damage.
Range MID 3.8 Recharge 0.55 s
Evolution
Crossfire
Sentry volleys pierce two more enemies. Ricochet adds a bounce beyond the main target.
Core 02
Lightning jumps between nearby Machines. Energy damage.
Range CLOSE 2.6 Recharge 1.20 s
Evolution
Thunderstorm
Arc charges enemies. If they fall within 3 seconds, lightning jumps to two more targets.
Core 03
Explosive shells punish packed crowds.
Range LONG 1.4–5.8 Recharge 2.40 s
Evolution
Cluster Barrage
Every mortar impact scatters three smaller explosive shells around the blast.
Core 04
A brief lock, then a piercing energy beam.
Range LONG 6.5 Recharge 2.80 s + 0.25 s lock
Evolution
Breach Lance
Lance pierces up to 6 Machines and deals 25% more damage. The lock line still warns before it fires.
Core 05
A flame cone sets close crowds burning. Fire damage.
Range CLOSE 2.6 Recharge 2.00 s
Evolution
Firestorm
A Machine that dies burning flashes over, setting Machines beside it alight. Incinerator also burns hotter.
Support EMP: Automatic disruption support. It is never a starting core; drafts can install it.
03 Levels
Finish wave 77 on one level to open the next. A boss attacks on waves 10, 20, 30, 50, 60, and 70; the level’s Mega Boss on waves 40 and 77.
01 / 04 Open from the start
Balanced Machines. Start here.
No permanent damage resistance.
Mender Menders repair other Machines within 1.5 of them by 4% of their health each second. They never repair themselves or bosses, and EMP stops them. Destroy Menders first. 
Mega Boss · waves 40 and 77
Bastion Breaker
Two relay escorts power its armor. Destroy each relay to strip a layer.
02 / 04 Finish Core Perimeter to open
Plated armor resists Sentry. Mortar and Shatter hit harder.
Plated Machines take 25% less Sentry damage and 25% more blast damage.
Breacher Breachers are heavy pushers. They wear the shield down twice as fast as Treads and cost 4 integrity if they reach the core. 
Mega Boss · waves 40 and 77
Foundry Breaker
03 / 04 Finish Foundry to open
Insulation resists Arc and Lance. Sentry hits harder.
Insulated Machines take 25% less Arc and Lance damage and 25% more Sentry damage. EMP still disrupts them.
Jammer While a Jammer is within 2.4 of the core, your guns fire 15% slower. More Jammers do not slow them further. EMP disrupts a Jammer and keeps its own cycle. 
Mega Boss · waves 40 and 77
Relay Breaker
04 / 04 Finish Relay Yard to open
Blast lining resists explosions. Arc and Lance hit harder.
Blast-lined Machines take 25% less blast damage and 25% more Arc and Lance damage.
Hive A destroyed Hive releases three Gnats: small, fast Machines that carry its lining. Gnats release nothing. A Hive that reaches the core costs 2 integrity. 
Mega Boss · waves 40 and 77
Fragment Breaker
04 Difficulty
Chosen per level before a run. Stronghold’s difficulties are its own: the same level, with tougher or gentler Machines and a stronger or weaker shield.
01
Machines have 30% less health and wear the shield down 30% slower. The shield is 30% stronger.
02
The level as tuned.
03
Machines have at least 25% more health and wear the shield down 50% faster. The shield is 20% weaker.
05 Drafts
49 upgrades in the pool, including five evolutions: Crossfire, Thunderstorm, Cluster Barrage, Breach Lance, and Firestorm.
A draft follows waves 1, 2, 3, 5, 7, and 10, then every three waves from wave 13 to wave 76. Each one offers a handful of upgrades; you pick one.
Optional draft actions
These cost Intel; choosing an upgrade is always free.
Endless has no draft purchases.
06 Events // Medals // Workshop
Some waves carry an event (waves 12, 15, 18, 22, 25, 28, 32, and 38 of a level): meet its goal for a reward. Clear a level under a medal’s condition to earn it, and medals unlock Workshop perks.
A marked Treads arrives 6 seconds in. Destroy it before it reaches the shield, or the core once the shield is down, to earn +10 shield (or +2 integrity once the shield is down).
Finish the wave without the shield losing strength (or the core losing integrity, once the shield is down) to fully charge Overdrive.
Clear the wave within 20 seconds of the last Machine arriving to earn +2 integrity (or +5 shield if integrity is full).
Clear the level without the shield falling.
Clear the level without choosing a repair.
Clear the level with your starting core as the only damage weapon.
Three perk slots open as you earn medals: the first from the start, the second at 6 medals, and the third at 12 medals. The Daily Defense runs without perks.
07 Endless // Daily Defense
Two ways to keep going, each with Game Center leaderboards: four Endless boards (one per level) and a Daily Defense board.
From wave 78
Clear a level's wave 77 and choose CONTINUE INTO ENDLESS to keep the same defense going until the core falls. A boss comes every 10 waves, a Mega Boss with its relays on wave 120 and every 40 waves after, a draft after every 5 waves, and an event on waves ending in 2 or 7. Machines grow tougher every wave. Existing banishes carry over; Endless has no draft purchases. The best wave you clear ranks on the level's Game Center endless board; Relaxed runs are unranked. No Intel is paid past wave 77.
New each day · midnight UTC
One defense a day, the same seed and level for every player: Standard difficulty, any starting core. It starts at wave 1 and carries on past wave 77 until the core falls. Play it as often as you like; your best attempt ranks on the day's Game Center board, and a new defense starts at midnight UTC. No Intel, and it never touches your levels' saved defenses.
08 Basic Training
Six short lessons teach Stronghold’s controls, one at a time.
Your fortress fires automatically. Protect its shield and core.
Tap Deploy Choke Point to deploy the triangles together.
Machines are too close. Tap Repulse to push them back.
Tap Siege Shot, then tap the marked target. You can also drag from the button.
These Machines are rushing your core. Repulse is refilled for practice. Tap Repulse to stop their rush.
Overdrive is ready. Tap it to make your weapons fire faster.
