The free game is OMGPOP's take on Rock Band and Guitar Hero, whom they hope to rival with a more diverse selection of music, better music discovery through gameplay, music videos playing in the background (as opposed to animation), and the cost-free incentive.
Once you log in to OMGPOP, you can find Hit Machine accessible from the Games drop-down menu at the top of the page. When you're in, you'll be greeted with a big "Play Now" option, and a sidebar that shows you available matches, friends playing, and recent opponents. You can either play solo, invite a friend, join a match, or watch one in progress.
Gameplay is pretty simple in theory, albeit challenging in practice, and is certainly reminiscent of the console equivalents. With Hit Machine, you'll use keyboard letters ASD and JKL to control your instrument with your fingers, and time keyboard strokes with the rhythm of the bars on the screen. Gameplay can be quite addictive, especially with the opportunity to challenge friends and the music video as the backdrop for all the action.
Dan Porter, CEO of OMGPOP, told us that he only wanted to work with labels that got his vision, which is why you'll only see 65 tracks at launch from labels like Vice Records, Nettwerk, and Epitaph. He hopes, however, that his approach will prove to be band-friendly (the model rewards artists based on tracks played, music videos, and links to artist pages), and provide an enjoyable cost-free gaming environment for kids who can't otherwise afford the equipment associated with the console varieties.
If you're not ready to dive into Hit Machine, here's a quick video of what you can expect: