Mechanics

The mazing rule

The board is a 11×18 grid. Enemies walk the shortest open route from an entrance on the top row to the fortress at the bottom, recalculated every time the board changes. Towers are solid, so placing one reroutes that path.

You can never wall the enemy out. The game checks every placement before allowing it: it provisionally drops the tower, runs a breadth-first search from every entrance to the fortress, and rejects the placement if any entrance loses its route. Blocking is impossible by construction — lengthening is the entire strategy. A long snaking corridor keeps enemies inside your towers' range for far longer than a short one.

Two things ignore all of it. Flying enemies travel straight over your maze, and Brute stops to attack towers rather than walk around them. A maze that only answers ground pathing loses to both.

If the path is ever genuinely severed — disasters can destroy terrain and towers mid-wave — enemies attack whatever blocks them at 10 damage per second until a route reopens.

Economy

Kill gold is the enemy's reward value, and it decays as you go: the multiplier drops to 85% of its previous value at each biome transition, with a floor of 30%. Late waves pay far less per kill than their HP suggests, so economy built early compounds and economy built late mostly does not.

Each additional ⛏️ Gold Mine beyond the first costs 4g more than the last — 8g, then 12g, then 16g — which caps risk-free income stacking.

Selling returns 50% of everything invested in that tower, upgrades included. Repairs cost in proportion to the HP missing, never less than 1g.

The fortress

The fortress occupies a 3×3 footprint at the bottom-centre of the grid and has 50 HP. Every enemy that reaches it deals damage scaled to its type — from 1 for a Grunt up to 25 for a Boss. Reaching zero ends the run.

Spend gold on four upgrade trees, each 5 levels deep. The attack tree also arms the fortress itself: 10 damage at 14 cells range every 1.5s, with 1.5-cell splash.

Attack

Defense

• Level 2 — regenerates 5% of max HP between waves.
• Level 3 — takes 20% less damage.
• Level 5 — reflects 25% of damage back at the attacker.

Economy

• Level 3 — start each run with +5g.
• Level 4 — earn 5% interest on banked gold between waves, capped at 25g.

Buffs

• Level 4 — repairs 25% of every tower's HP between waves.

Wave scaling

Enemy HP scales with the wave number: base HP × (1 + (wave − 1) × 0.22). A wave-25 enemy therefore has 6.28× the HP its stat block lists.

In the campaign the wave counter is per level — it resets each time you start one. Wave 1 of the final level scales exactly like wave 1 of the first. That is why late campaign levels lean on raw enemy counts and nastier compositions rather than inflated HP.

Terrain

Campaign levels place terrain features as tetromino shapes, each rotatable in 90° steps. Terrain is impassable and unbuildable — it is free maze wall you did not pay for, and an obstacle when it sits where you wanted a tower.

Disasters

Optional in Classic and Random, and enabled on 22 campaign levels. From wave 8 onward each wave can roll a disaster; the chance accumulates per wave up to a 70% ceiling.

Scoring and stars

Score comes from three sources:

• Kills — the enemy's gold reward × 10.
• Wave clears — wave number × 50.
• Survival — remaining fortress HP × 100 on victory.

Campaign levels award stars on remaining fortress HP alone, against per-level thresholds listed on each level page. One star clears a level and unlocks the next; three requires finishing at or above the level's high-water mark. Game speed can be set to 0.5×, 1×, 1.5×, 2×, 4× without affecting scoring.