Tower defense guides quote upgrade prices from whatever clone they played. This site ships one engine in src/games/tower-defense/TowerDefenseEngine.ts, and its economy is fully written down. Every cost, hit point, and income figure below comes from that file.
The wave formulas
Waves are generated, not hand listed, and the generator fixes these counts.
1. Normal enemies number 6 plus 2 per wave, capped at 40. Wave 1 sends 6, wave 10 sends 24, wave 18 onward sends 40.
2. Fast enemies join at wave 3, starting at 3 and capped at 15.
3. Tanks join at wave 6, starting at 1 and capped at 8.
4. Bosses arrive every fifth wave, one on wave 5, two on wave 10, three on wave 15, four on wave 20.
5. Enemy hp scales by 1 plus 0.12 times the wave number minus 1. Wave 10 multiplies base hp by 2.08, wave 20 by 3.28.
Kill income is fixed per type: 10 gold for a Normal, 15 for a Fast, 25 for a Tank, and 100 for a Boss. Score adds double each reward. Summing the formulas, wave 1 pays 60 gold, wave 3 pays 145, wave 5 pays 300, wave 10 pays 650, and wave 20 pays 1225. You start with 200 gold and 20 lives, and kills are the only income in the game.
Tower math you can plan around
Base damage per second divides damage by fire interval. Arrow deals 30 for 50 gold. Cannon deals 33.3 for 100 gold plus splash. Ice deals 13.3 for 75 gold. Zap deals 27.8 against one target for 150 gold.
Zap is the outlier. Its chain jumps to up to 3 extra enemies within 2.5 grid units at 70 percent damage each, so a volley into a packed lane deals 76 damage across four enemies, roughly 84 damage per second spread. Against lone bosses it falls back to single target output.
Ice never kills efficiently. Its projectile applies a 50 percent speed penalty for 2000 ms, so its job is stretching the time enemies spend inside your damage towers. Fast enemies move at nearly twice normal speed, and Ice erases that advantage while the slow lasts.
Upgrade and sell arithmetic
Towers cap at level 4. Upgrades cost the base price times 1, then 1.5, then 2.5. Each level multiplies damage by 1.4, adds 0.3 range, and multiplies the fire interval by 0.85, floored at 150 ms.
An Arrow reaches level 4 for 300 total gold. Its damage climbs 12 to 16 to 22 to 30 and its interval drops 400 to 340 to 289 to 246 ms, landing at about 122 damage per second with 4.1 range. A maxed Cannon costs 600 total and reaches about 148 damage per second with a 1.8 splash radius. Upgrading two Arrows outdamages one new Cannon per gold spent early, while the Cannon splash matters once waves pack 20 or more enemies.
Selling refunds 60 percent of everything spent, so repositioning always loses 40 percent. Place deliberately.
The deterministic opening build
1. Spend 100 on two Arrow towers before wave 1. One Arrow kills a wave 1 Normal in 2 seconds, and six arrive on a 700 ms interval.
2. Add one Ice for 75 before wave 3, when Fast enemies first appear with 35 hp each.
3. Save toward 150 for a Zap before wave 5. The wave 5 boss carries 1184 hp after scaling, and single target arrows alone will not stop it from leaking.
4. Buy your first Cannon before wave 6, when Tanks arrive with 320 scaled hp.
5. Convert your two Arrows to level 4 across waves 7 to 10, total 600 gold, before the two boss wave at 10.
6. Call waves early only when your towers are idle. The 8000 ms auto timer between waves gives free building time, and pressing NEXT or Space early pays nothing, so there is no reward for rushing.
Placement follows two engine rules. Towers always shoot the enemy furthest along the path within range, so deep coverage near the exit protects you against leaks. The path serpentine revisits columns 2 and 16 and rows 3, 10, 17, and 24, so cells beside those junctions put several path segments inside a 3.0 or 3.2 range circle. Buildable ground spans rows 2 to 29 anywhere off the path.
Honest limits
A leaked boss costs exactly one life, the same as a leaked Normal, so late game leaks feel worse than they score. Wave composition is shuffled inside each wave, so spawns cluster unpredictably and chain targets vary run to run. There is no interest on banked gold and no bonus for early wave calls, which removes two classic economy tricks. Best wave and best score persist under localStorage key tower_defense_stats, and clearing site data deletes them.
Tower defense build checklist
- [ ] Two Arrows placed before wave 1 starts.
- [ ] Ice online before wave 3 Fast enemies.
- [ ] Zap funded before the wave 5 boss.
- [ ] Cannon in place before wave 6 Tanks.
- [ ] Arrows at level 4 before wave 10.
- [ ] Junction cells used for multi segment coverage.
- [ ] No early NEXT press while towers idle.
Play the [tower defense game](/en/tower-defense) and track your gold at each wave boundary against the income figures above. If your clears cost more gold than this plan allows at any wave, send us the wave number and your tower list. Failed builds by wave are the most useful data you can send.
