Aliens: Colonial Marines isn't actually out until next week, 2K Games already has some DLC lined up. Not to mention a season pass system, something most gamers are familiar with by now.
Priced at $29.99 (or £19.99/€29.99/$29.99/2400 Microsoft Points, depending on your system and region), the season pass grants access to four upcoming Colonial Marines add-ons, including the very first, "Bug Hunt." This is a Horde-esque multiplayer mode, pitting players agains waves of increasingly difficult baddies across three environments based on the Aliens movies.
"Bug Hunt" will be out some time in March, but don't expect early access or anything. Picking up the season pass just means you're pre-purchasing the DLCs at a discounted price -- around 40%, according to 2K.
On the bright side, the season pass doesn't look like an actual requirement for playing the multiplayer and co-op (unlike so many others). Good thing too, because it isn't included with new copies of the game.