One keep. Endless waves. Every upgrade is a decision made while the fight is still on.

Endless Bastion is an idle, incremental tower defense game built around a single keep. It fires automatically while enemies advance from every direction. Spend cash during the battle to shape your build, survive boss waves, then bring shards home to make the next run stronger.

UPGRADE WHILE ENEMIES ATTACK
Combat keeps running when you open the upgrade sheet. Buy damage, attack speed, range, critical hits, multishot, ricochet, health and more while enemies are closing in. Each card shows what you have, what comes next and what it costs. Your keep changes as it grows, from rising stonework to a brighter crystal crown.

FALL, BANK SHARDS, RETURN STRONGER
Cash and run upgrades reset when the keep falls. Shards stay with you. Spend them in the Workshop on permanent upgrades so every run can push farther. Unlock eight arenas, from Forest and Desert to Volcano and Graveyard. Each new ground brings tougher enemies, a new look and a higher shard payout. Bosses arrive every ten waves.

BUILD YOUR OWN DEFENSE
Unlock the Tesla Coil, Mortar, Ballista, Flamespout, Prism and Spiked Flail. Add a Bastion Wall to hold enemies back. Bring companions into the fight: Raincloud slows and strikes, Dust Devil pushes, Frost Sentinel freezes, and Magma Hound leaves burning pools. Equip up to two companions together. Draft perks during a run and collect boons that carry into future battles.

RESEARCH THROUGH COMBAT
Research advances from kills while you play, not from a countdown timer. Open more research slots as you reach milestones, then choose which improvements to pursue. Upgrade your attack, defense, income, companions and weapons over time.

IDLE SHARDS BETWEEN RUNS
A completed run earns shards while the app is closed, starting with a 12-hour offline window that research can extend. Offline earnings do not play waves or advance research. When you return, speed controls and Onslaught help you cross ground you have already cleared and get back to the frontier.

MORE TO DISCOVER
Complete daily contracts for shards, fill a bestiary as you meet new enemies, and chase your best wave on each arena. Play in portrait or landscape, orbit the arena with one finger, and pinch to zoom. Google Play Games achievements and leaderboards track your progress, with manual profile backup and restore through saved games.

No energy timers or lives to refill. Ads are optional rewards that you choose to watch. The fight is yours to build, one wave at a time.