Economy balance is the slowest, hardest part of designing an idle tower defense. This devlog walks through how we approach it: the curves, the testing, the player-data dashboards, and the lessons from when we got it wrong.

On this page

Direct answer

The Lost Tower economy uses multi-currency design with explicit interaction rules between layers. We tune by watching player progression rate, retention curves, and currency hoarding behavior. When we get it wrong, players notice within hours.

Why economy matters

An idle game economy is the spine of the experience. Tune it too generous and players hit endgame in days, then leave. Tune it too tight and players quit before they reach the interesting layers. The economy decides the pacing.

What we measure

For every balance change, we watch four metrics:

  • Time to milestone. How long until players reach key progression points (first ascension, first Epic parchment, wave 100).
  • Currency velocity. Are players spending what they earn, or hoarding? Hoarding usually means upgrades feel undervalued.
  • Day-2 retention. Does the economy make players want to come back tomorrow?
  • Day-7 retention. Does it make them want to come back next week?

The currencies

Lost Tower has four currencies. Each is earned through different actions and spent on different things.

  • Gold: in-match currency, resets between matches
  • Shards: earned from wave completion, spent on persistent tower levels
  • Essence: god-specific currency for ascension
  • Marks: meta currency for parchment draws

Tuning a curve

When we adjust a currency curve, we change one variable at a time and observe for at least 48 hours before changing more. Multi-variable changes are tempting but they make diagnosis impossible. Discipline is essential.

For each change, we ask: does this make the next session more interesting? If the answer is no, we revert.

When balance goes wrong

It goes wrong often. The most memorable: in B0.3, we accidentally made shards 4x more generous than intended. Players reached endgame in two days. Engagement collapsed. We corrected within 36 hours, but the damage to that cohort took weeks to recover.

The lesson: economy is a system, not a spreadsheet cell. Changing one number always changes everything downstream.

Next devlog: the four gods system.