Every hero changes the heroes beside it

Formation Builder Idle is an idle RPG about placement. Your heroes fight on their own, but where you put them decides how hard they hit. Move one hero by a single slot and your damage can change by orders of magnitude.

A puzzle made of 46 heroes

Every ability reads the grid. Some heroes buff their neighbors, some buff a whole column, and some care about traits or the entire formation.

Lorn buffs every neighbor, and gets stronger for each neighbor and each different trait among them.
Perrin copies the buffs aimed at him and passes them to the column in front.
Nerissa gets stronger the more positional buffs point at her.
Falgrim counts the traits he shares with his neighbors, and his bonus grows with the square of that count.

With 17 traits, gear on every hero and a scarf stat that strengthens that hero's ability, the best layout keeps changing as your roster grows. Save several formations per world and switch between them.

Left-click levels a hero. Right-click buys max.

Prestige across 21 worlds

Push until the waves stop you, then prestige. Your gold becomes talent points to spend across 99+ talents, and each world pays out its own World Essence. There are 125 stages to clear, and World Mastery rewards you for going back to earlier worlds with a stronger team.

Mounts and the Tower of Domination

There's a second combat game inside the first. Collect 12 mounts, level them up, give them hero riders and build teams around 6 terrain elements for a 100-stage mount campaign. Then take them into the Tower of Domination, a weekly 1v1 climb where leaders don't count and only mount stats, abilities and elements decide the fight.

Heroes who aren't fighting still work

Missions. Send spare heroes on timed missions. The crew planner shows your success chance before you send anyone.
Mines and the Workshop. Put heroes to work as miners and station workers for resources and permanent DPS bonuses that survive prestige.
Pets. 13 pets that either buff a hero or go farming for Pet Treats.
The Seer. Spend Diamonds on permanent bonuses to DPS, gold, talent points and mount power.

Progress while you're away

Close the game and your formation keeps fighting. When you come back, the server works out the gold, waves, chests and mine resources you earned while you were gone.

One account on every platform

Play on Windows, Mac, Linux, Android or in your browser, and your progress follows your account. Leaderboards show how you stack up against other players.

Early Access from a solo developer

I'm building Formation Builder Idle on my own. Since May 2026 I've shipped more than 20 updates, many changes start as player suggestions, and every patch note goes up here and on Discord.

Free to play

Formation Builder Idle is free to play. Purchases are optional and speed things up. Every hero, pet and feature, including Auto Farm, can also be earned by playing. Chest odds and pity are shown in game.