All in the Game — R. Ann Siracusa

When romance writer Shauna Evans agrees, as a favor to her agent and friend, to help computer genius, Don Kennedy, write a computer game to appeal to women, she has no idea he is also a physicist doing research with artificial intelligence and virtual reality for NASA.When a test run in a simulator goes awry, Shauna and Don find themselves transported physically into the video game as game characters on the planet Ethros in another galaxy. The only way they can return to their reality is to work together and win the game by playing it from the inside. Unfortunately, their game characters, Commander Shauna and Captain Don, are enemies on opposite sides of a war.