Plants vs. Zombies has been a bit of a cultural phenomenon at times, and EA is giving away the definitive version of it via Origin. The On the House program strikes again and offers up a mix of action and tower defense. It's playable on both Windows and Mac platforms, and is a ton of fun. It's definitely not for everyone, but as a gateway game for those looking to try out tower defense games, it's a great starting point. It will also run on just about anything that exists on Earth right now in terms of horsepower - and that means that anyone with an internet connection should be able to enjoy it and see what the hype has been about for the past half-decade.