Pick a bid

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Return on ad spend

Google Ads measures an ad by return on ad spend (ROAS): money the ad brought in ÷ money spent on it × 100%. Google's example: $5 of sales from $1 of ads is a ROAS of 500%.

For a game, the money keeps coming in for months, so Theo measures ROAS by day: day 7 ROAS, day 30 ROAS, and so on. The ad has paid back on the day ROAS reaches 100%.

Theo's payback curve

Theo takes last spring's paid players and adds up what each brought in, after the store's share, by day since install. The curve rises fast at first, then slowly, as most players stop playing.

Shard Garden's rule: an ad must pay back within 180 days.

Do the math

earned per paid player
Day 7       US$0.30Day 30      US$0.60Day 90      US$0.90Day 180     US$1.10Day 365     US$1.30

Theo pays US$1.00 for each install. What is the day 30 ROAS?

  1. 60%
  2. 100%
  3. 167%
Show the answer

60%

US$0.60 earned ÷ US$1.00 spent × 100% = 60%. The ad is still 40 cents short on day 30. It reaches 100% between day 90 and day 180.

Try it

Pick a bid

A higher bid wins more ads and brings more players. Find the bid that brings the most players and still pays back within 180 days.

Try it in the lesson

Design review

Kai, #growth
The US$1.40 bid brings 10,000 players a month. Let's go big.

What does Theo answer?

  1. After a year, a player has earned US$1.30, still short of US$1.40: that bid never pays back
  2. More players always means more money
  3. The bid only matters for the first week
Show the answer

After a year, a player has earned US$1.30, still short of US$1.40: that bid never pays back

Every player bought at US$1.40 costs more than they bring in over a whole year, so 10,000 of them lose money 10,000 times.

Cash waits for the curve

At US$1.00, Shard Garden buys 7,000 players a month for US$7,000. Each month's players repay their US$7,000 slowly, over about 135 days.

Meanwhile the studio keeps paying for new players. By the time the first month pays back, about four and a half months of spend, US$31,500, has gone out. Some has come back, but the studio needs the cash in the bank to wait.

Quick check

Theo doubles the spend to US$14,000 a month at the same bid. What happens?

  1. The payback day stays the same, and the cash the studio must hold roughly doubles
  2. Payback comes twice as fast
  3. Nothing changes
Show the answer

The payback day stays the same, and the cash the studio must hold roughly doubles

The same bid buys the same kind of player on the same curve, so payback still takes about 135 days. Twice the spend waiting means twice the cash out.

Judge early, act early

Waiting 180 days to learn that an ad failed is expensive. In Theo's past campaigns, a day 7 ROAS of about 30% has led to payback within 180 days.

So each new campaign gets a small budget for a week. If its day 7 ROAS is far below 30%, Theo cuts it, without waiting months for proof.

Quick check

A new campaign shows a day 7 ROAS of 12%. What should Theo do?

  1. Cut its budget now: it is far behind campaigns that paid back
  2. Wait 180 days to be sure
  3. Raise the bid, to get more players
Show the answer

Cut its budget now: it is far behind campaigns that paid back

12% is well under the 30% that past campaigns needed at day 7. A higher bid makes each player cost more, so it pays back even later.

On the studio board

The studio adds a decision to the board:

Paid ads: payback within 180 days. A new campaign runs a week on a small budget and stops if its day 7 ROAS is far below 30%. The cash plan holds about four and a half months of ad spend.

Bolt says: Next: dashboards for the team.

Fact-checked 12 October 2026