The first game was not something easy to get in to. I don't remember if it had a tutorial either. It needs one. This is probably why only the hardcore players remain with the first game.

On the human side, you need a competent commander and players who can follow orders. On the alien side, you need your builders (Gorge unit) to construct and while they can construct as much defensive towers as they want, the upgrade towers were a topic of discussion. If you constructed an upgrade that masked your sound for example, you couldn't build an other type of upgrade until you had gained an other hive.

I'm not sure how the sequel will work, I think I read the aliens might have some sort of commander?

Small video of the gorge unit:
http://www.unknownworlds.com/ns2/news/2009/8/gorge_reveal

For those who pre-order the game, you get access to play the beta version and help balance the game and what not. If you buy the special edition, you get to play the even more buggy alpha version to help them get rid of even more bug. (It shouldn't feel too different than playing TF2 in that aspect :p)

I will pre-order it once I see it on Steam. Since it's their first commercial game, I would rather be sure the game is coming out before spending money.

Video footage from the pre-alpha:
http://ve3d.ign.com/videos/61817/PC/Natural-Selection-2/Gameplay/Pre-Alpha-Gameplay-Movie

It looks quit good visually (Beside the low frame rate).

http://www.unknownworlds.com/ns2/news/2010/3/friday_update_engine_test_status

On April 9th, a "test engine" for NS2 will be released. They will use this to iron out the bug so they can release the Alpha version. The engine will be available for anyone who pre-order both version of the game. I don't know if this include gameplay or just walking around as marine or alien. Still, it's a good news and gives hope that the game will come out at some point.

http://www.youtube.com/watch?v=7bpcA0S0pBc

I didn't expect a "funny" trailer from the NS people but there it is. This is a "teaser" trailer for the Fade. Teaser as in, you'll only get to see half a second of a fade shadow over a drowsy or drunk Gorge. Still, totally worth it.

What exactly is this game again?

It's what will kill TF2, I hope. It's a game about Aliens versus Marines. The first game was really popular, probably as much as CS back in the days but unlike CS, it died out due to its complexity(I assume).

It's a FPS with some RTS elements. I think in the sequel, each side as a commander who see everything from a top-down view and can give orders. In the first game, only the marines had a commander. He would say where to build stuff and marines had to go there and build it, using the "use" key. It was simple. Base on how that went, you had a tech tree and the commander could increase armor or weapon damage, build a radar to detect aliens, give special weapons, heavy armor, jetpacks, etc.

The aliens on the other hand had a unit responsible for building called the Gorge. That's the one you see in the video. He would go around building defense tower and upgrade tower. Each upgrade tower gave a bonus to aliens such as better armor, better sensory input or even cloaking while standing still.

I have high hopes for this game. If it's anything like the first, I could be playing this for a long time.

Video showing the hydra defensive alien towers in action. It's pretty neat! When they "perk-up", it means marines are nearby.

http://www.youtube.com/watch?v=WoWiRv9JJzo&feature=player_embedded

So you barf up spiky plants for defense? Awesome!

Alpha is starting at the end of this month for people who ordered the special edition. (I'll buy once the game is near release) There are a few screen shots of what to be expected and it's really cool that they finally reached this milestones.

http://www.unknownworlds.com/ns2/news/2010/7/ns2_alpha_date_set

-- Update

While the game is currently 20$, the price will go up at the end of this month. They haven't said by how much.