One way to start playing in in-game advertising - forget middlemen; buy a game maker. WPP has acquired a minority stake in Dundee, Scotland-based game developer Realtime Worlds for $8.1 million. It’s part of a total $50 million second round funding, led by Maverick Capital and joined by New Enterprise Associates, that’s pitched toward general “continued expansion”.

Founded in 2002, Realtime Worlds’ founder David Jones previously made Lemmings and Grand Theft Auto, employs over 200 staff and has offices in Boulder, Colorado. A 2006 first round of $31 million came from New Enterprise and the company went on to make the MMOG APB and X-box 360 action title Crackdown.

For WPP, it’s a step further to placing its clients’ ads in new game worlds, without buying a dedicated game ads agency as Microsoft (NSDQ: MSFT) did with Massive. In 2006, it invested $3 million in WildTangent, a game network that it was already using to display ads in. WPP: “WPP’s investment in Realtime Worlds builds on the interest in new online advertising formats and content.” Other in-game ad nets include IGA.

• Game Publisher/Ad Network WildTangent New $13 Million Round Includes $3 Million Firm From Sorrell’s
• Microsoft Does Buy Massive; Part of AdCenter Platform