Buy order, prestige timing, gem spending and the offline math — reasoned from the game's actual numbers, not guesswork.
In short: buy milestone upgrades before new buildings, don't let coins sit idle, and don't wait too long to prestige — earnings need to 8× to double your gems, not 2×. Spend gems on Starting Capital and Golden Touch early; save Diamond Mine for once you're prestiging often.
A building's price rises 15% per copy, but its milestone multipliers are flat purchases that don't get more expensive the more buildings you own. See the buildings page for the full cost table, but the shape of it is always the same: the ×2 upgrade at 10 owned costs a fraction of what the next handful of that building would cost you, and it doubles every copy you already have — including the ones you haven't bought yet. As a rule, if you can afford a ×2 milestone upgrade for a building you're actively growing, buy it before the next batch of that same building.
Two upgrade types compete for the same coins, and they're not equal:
Gems from a prestige are the cube root of that run's total earnings: gems = floor(10 × (earnings ÷ 1,000,000,000)⅓).
A cube root grows slowly, so the earnings required for each gem milestone climb fast:
| Gems | Run earnings needed |
|---|---|
| 1 | 1M |
| 10 | 1B |
| 20 | 8B |
| 50 | 125B |
| 100 | 1T |
Two facts fall out of that table and they're the whole strategy: doubling a run's earnings only yields about 26% more gems (2⅓ ≈ 1.26), and going from 10 gems to 20 needs 8× the earnings, not 2× (2³ = 8). Income keeps compounding the longer a run goes, but gems fall further and further behind it. Grinding a single run for hours past the point where you've bought every milestone upgrade you can afford earns you steadily less gem-per-minute than starting a fresh run would.
Practical signal: once you're only adding flat building counts and not crossing new milestones or affording new upgrades, that run has stopped compounding — prestige. If you own the City Hall landmark, its flat +1 gem also matters more early (when a formula result of 2–3 gems means +1 is a 30–50% bonus) than late, when +1 gem is a rounding error.
Prestige unlocks only once every one of the six districts has at least one building and the run would yield at least one gem.
Every unspent gem is worth +2% to all income on its own (the gem aura), so gems are never wasted sitting in your balance while you save up. Spending them converts that ongoing aura into a permanent shop perk instead. A reasonable order, cheapest and most universally useful first:
Timing tip: because the aura is 2% per unspent gem, spending gems always costs you some income while you don't have them anymore. That cost is smallest right after a prestige, when your income for the run is at its lowest point — so time expensive purchases for right after you reset, not in the middle of a long run.
Offline production runs at 50% efficiency compared to active play, capped at 4 hours by default. With Long Memory that cap is 8 hours, and the Convention Hall landmark adds another 10% on top — 8.8 hours with both. At that combined cap, a full absence credits 4.4 hours of your current income rate. Roughly: check in about once every 9 hours if you have both, or every 4 if you have neither, to never lose accumulation to the cap.
Absences under a minute are credited silently with no popup; anything longer shows a summary when you return.
A golden gull appears every 3–7 minutes during active play (never while the game is closed) and stays on screen for 13 seconds. With Faster Gulls, the City Park landmark, and the Gold Fever achievement (tap 50 gulls) all combined, the average wait drops from 5 minutes to about 3.5 minutes.
Double Luck is worth being precise about: it adds +30% specifically to the one-off Lucky Break and near-miss payouts. It does not extend or strengthen Gold Fever, Blood Moon, or Click Frenzy — those stay fixed at ×7 income for 30/20 seconds and ×777 taps for 15 seconds regardless of any gem shop purchase.
The best tap of the game: a critical tap (from the Critical Strike upgrade, 5% chance, ×10) landing during Click Frenzy (×777) stacks multiplicatively — a single tap worth 7,770× its normal value, not 777×. Buy Critical Strike before you start relying on Click Frenzy bursts.
Landmarks are one-off purchases for the current run only — prestige wipes them along with everything else except gems, achievements and gem shop purchases. Since they reset anyway, there's no penalty to buying one late in a run specifically to push toward a prestige threshold; there's no benefit to rushing one early if you weren't going to use the map decoration.
Achievements are the opposite: permanent, and they survive every prestige. There are 19 of them, and together they add up to +53% permanent income if you complete every one — a bigger total bonus than any single gem shop item, earned by playing rather than bought.
For the exact per-building numbers behind all of this, see the buildings page. For the base mechanics, see how to play.