After clicking the "Install Game" button, it says it's registered to my Steam account, and the page now says I own it. So I'm pretty sure this is another giveaway rather than a demo.
I've played a few of the games in the pack, they were alright... I didn't try any of the adventure games, maybe they have more character.
Alpha Prime is a decent shooter, looks a bit similar to Red Faction 2 but with better graphics. Ran fine. A surprisingly complete plot is delivered by several voice acted NPCs, mostly over radio, with their own agendas. It's nothing too innovative or complex, but it does the job well. There's a gimmick of hacking security cameras and turrets wirelessly, it's not a factor in most fights which keeps it from getting repetitive. Final boss was cool.
Space Trader Merchant Marine is too bland and repetitive. Trading is boring and mostly pointless, and the sub-missions on each world are impossible to take seriously. The shooting is very basic. I don't remember most characters being VA'd. Budget title, and it shows.
Obulis: If you want a puzzle game like this, you're better off on a Flash arcade.
Penguins Arena: Same... I think this was part of the Portal 2 potato ARG. Never played it again.
Vigil Blood Bitterness: I launched this and couldn't figure out what anything was. I think it was just an obtuse artsy UI, but maybe it was actually broken. Uninstalled. Kinda like EYE but way less playable (Which, despite EYE's redeeming qualities, is saying something)
Tank Universal: Interesting game. Centered around strategic first-person tank combat, with resource production and structures. I found it too difficult, but it's worth the current $1.24 and I'm reinstalling it now.
I recommend going through the list, at least. Most of the games are $1.24, and I bet most of the adventure games are probably worth that in B-movie value.