If you're looking for some real gameplay footage, check out this livestream of the alpha.
Halo Online is a new free to play Halo game for PC that's launching a closed beta this spring in Russa. It's likely to be full of microtransactions and possibly be terrible, but the game is said to be launching in Russia in an effort to combat the rampant piracy there. Can't steal a game that's already free! There are no current plans to expand the game outside of Russia, but "theoretically, any expansion...would have to go through region-specific changes to address player expectations."