By 
Want to play Tomb Raider: Underworld for free? Now you can. Square Enix have added the game to their Core Online service, which allows you to play a few of Eidos’ console games in your browser without having to pay anything.
Core Online is supported by ads. An ad will pop up periodically (usually every 20 minutes) and you’ll be given the option of watching through it or paying a certain amount to remove ads. The longer the ad, the more game-time you earn.
You can either pay to remove ads across the entire game or just purchase ad-free play-time for individual levels. Something to note is that the Core Online service doesn’t “stream” data to your browser—it pre-loads it, which means games run pretty smoothly.
Other games currently on Core Online are: Hitman: Blood Money, Mini Ninjas, and Lara Croft and the Guardian of Light.
