The idle layer is what makes Lost Tower an idle tower defense rather than just a tower defense. This devlog explains how we designed it: the math we used, the design philosophy we settled on, and the iterations it took to get there.
On this page
Lost Tower's idle layer is designed around a 40-60 active-to-idle ratio: active play is roughly 40% more efficient than idle for the same time investment. This ratio is intentional. Active play feels rewarded; idle play feels meaningful; neither dominates.
The principle
Idle progression should reward consistency without punishing irregularity. A player who plays an hour every day and a player who plays five hours on Saturday should both feel productive. The first never should feel they could have done more. The second should never feel they wasted time by being away.
The first idle layer (and why we threw it out)
Our first idle implementation was too generous. Idle progression was 90% of active progression. Players stopped playing actively because there was no point. Engagement dropped. We pulled it after two weeks.
Our second attempt overcorrected. Idle was 20% of active. Players who played in short sessions felt punished. We pulled this too.
We landed at 60% (idle relative to active) after three more iterations. It is the ratio that makes both modes feel valid.
The active vs idle ratio
Why 60%? Two reasons.
First, it preserves the value of attention. Active play has to feel meaningfully better than idle play, or the entire active layer becomes irrelevant. 60% feels meaningfully worse than 100%, but not punitively so.
Second, it respects time. A player checking in once a day for ten minutes gets a meaningful return on that time. They do not feel left behind by players who can play more.
Diminishing returns on offline time
Offline gains diminish after a certain duration. We tested several curves and settled on capping meaningful idle gains at around 12 hours. After that, gains continue but at a steep falloff. This prevents the "checking in once a week" exploit while still rewarding overnight progress.
This was controversial in our community. Some players wanted uncapped idle. We chose the cap because it preserves session value.
The God of Time problem
The God of Time was our hardest gameplay design problem. They are the patron of idle progression. They need to be meaningfully different from the other three gods, who reward active play. But they cannot trivialize the active layer.
Our solution: God of Time provides idle multipliers and prestige scaling but underperforms in active matches. Players who serve Time are betting on the long game. They give up short-term performance for compound returns. See our God of Time lore page for the design philosophy.
Next devlog: balancing the economy.