Gaming can now be measured with the same causal rigor as CTV and social, through geo holdout testing that isolates incremental lift rather than just counting impressions. What has historically blocked that measurement isn’t the method, it’s fragmented inventory that makes a clean holdout test hard to run. This guide covers how incrementality testing works, why gaming has lagged, and what a properly structured test requires.
The measurement gap gaming has been stuck in
Gaming reaches audiences on a scale comparable to CTV and social, yet it routinely sits in the “experimental” tier of a media plan. The reason isn’t reach. It’s that gaming has typically been evaluated on exposure metrics, impressions, viewability, completion rate, while CTV and social increasingly get evaluated on causal ones. Exposure metrics confirm an ad was seen. They say nothing about whether the ad changed what anyone did.
Incrementality testing closes that gap. It’s the same standard other channels already meet, and there’s no structural reason gaming can’t meet it too, provided the inventory behind the test is structured correctly.
What incremental lift measures, precisely
Incremental lift is the portion of sales or conversions a campaign caused, isolated from what would have happened without it running at all. It’s distinct from attribution, which assigns credit to the last touchpoint a customer saw, regardless of whether that touchpoint influenced anything.
The standard method for isolating lift is a geo holdout test. Similar markets get divided into a test group, where the campaign runs, and a control group, where it’s withheld. After the test window closes, sales in the two groups get compared, and the gap between them is the lift. This design produces a causal estimate rather than a correlation, which is what makes it more rigorous than attribution-based reporting.
The evidence for the method is substantial. A dataset spanning 225 geo and holdout experiments found a median incremental return on ad spend of 2.31, with 88.4% of well-designed tests reaching statistical significance. Despite that, the IAB’s State of Data 2026 report found only 39% of organizations currently combine incrementality testing with their broader measurement models, a gap between what the method proves and how often it’s actually applied.
How incrementality testing relates to MMM
Media mix modeling and incrementality testing are frequently confused for competing approaches, but they answer different questions. MMM draws on historical data to estimate each channel’s contribution across a full media plan, which makes it suited to strategic, portfolio-level allocation decisions. Incrementality testing produces something narrower: one causal, real-world number for a single channel across a defined window.
The two methods work best combined. Leading measurement programs run geo holdout tests quarterly, then use the results to recalibrate their MMM’s coefficients. When a holdout result diverges from what the model predicted, the holdout is treated as the more reliable figure, and the model is adjusted to match.
Why gaming has been structurally harder to test
A geo holdout test depends entirely on control-market cleanliness, meaning the tested channel must be genuinely absent from the control group. That’s manageable with a single CTV or social platform. It becomes far harder with gaming, where inventory has traditionally been spread across dozens of publishers, platforms, and custom-built placements. Coordinating a simultaneous shutdown across five or six separate gaming vendors, in the same markets, at the same time, is where most attempted gaming holdout tests fail before results are even collected. A single contaminated control market invalidates the entire test.
Consolidated gaming platforms remove this obstacle by routing reach through one buy and one operations team instead of a patchwork of vendors. Overwolf Ads is one example: it spans more than 1,500 titles and 500-plus gaming websites under a single buy, structured across three formats.
Because the entire footprint sits under one operational layer, a brand testing gaming’s incremental contribution can apply a geo exclusion at the campaign level without separately coordinating a shutdown across multiple platforms, which is typically the step that breaks a multi-vendor gaming holdout before it produces a usable result.
Bottom line
Gaming doesn’t require a bespoke measurement standard. It requires the same one already applied to CTV and social, run consistently: matched test and control markets, spend held constant outside the test group, and a window long enough to detect lift above ordinary sales variability. Consolidated inventory is what turns that from a multi-vendor coordination problem into an operationally realistic test, and a clean lift result is what finally lets gaming calibrate into the same MMM as the rest of a media plan.
FAQ
Q: What separates incremental lift from standard attribution?
A: Attribution credits a single touchpoint a customer saw last, regardless of whether it influenced their decision. Incremental lift is measured through a controlled geo holdout comparing test and control markets, isolating sales the campaign actually caused.
Q: How often should a geo holdout test be repeated?
A: Quarterly testing is the cadence used by the strongest measurement programs, since it keeps MMM coefficients current rather than letting a channel’s estimated contribution drift out of date between full model rebuilds.
Q: Can gaming inventory be excluded from specific markets for a clean holdout test?
A: It depends on how consolidated the inventory is. Overwolf Ads operates its full ecosystem of titles and sites as a single buy, allowing campaign-level geo exclusions to be set directly rather than negotiated separately across multiple gaming vendors.
Q: Does a gaming lift result actually get incorporated into a media mix model?
A: Yes. A geo holdout result from Overwolf Ads spend can calibrate an MMM’s coefficient for gaming the same way a CTV or social holdout result would, provided the test markets weren’t simultaneously exposed to other gaming vendors’ inventory.