Mobile and video in-game ad platform Tap.me has been acquired by MediaMath, a global digital media-buying platform. Prior to the acquisition, Tap.me had raised more than $4 million of venture capital from a bevy of investors, including Hyde Park Venture Partners, I2A Fund, Hyde Park Angels and Great Oaks Venture Capital. The acquisition allows MediaMath, itself venture-backed, to become a programmatic buy-side platform that can deliver ROI across all digital marketing channels. The entire Tap.me staff will join MediaMath. Tap.me CEO Matt Spiegel will join its executive team as senior vice president and GM of Open, MediaMath’s business and technology environment for digital interoperability.