What are the stars next to the games?

It's a bundle game...
Now close this topic.

Someone should read the FAQ ;)
These are Bundle games.

Bundle games

It means they are bundle games.

or to give an answer thats actually helpful....
(what does it actually tell him to say "bundle games /thread"? how is that an answer?)

It means it was once in a bundle (and so from that point forward it is assumed that all copies were from the bundle) which means that the contributor value you get from them can't exceed $30 unless you also give away other non asterisked games(at which point it can go up by 20% of non bundle game value)
I'll have to check for the exact formula but pretty sure its
bundle games value cap= 20% of non bundle games +$30

you're free to gift more after hitting the cap it just won't do anything for your contributor value until you gift something else too(some giveaways can have a min contributor value to enter)

(if you see a bundle that isn't marked with an asterisk don't think you found one they missed or can get full value credit by gifting quickly before they mark it, when they do get around to marking games the asterisk is backdated to the bundle's start(it sounds like even if the game was a mystery item that didn't actually get added until a week later like airbuccaneers so you could gift it before it was ever in a bundle and it'll get marked like it was) and values get recalculated to reflect the asterisk(although tbh some bundles don't get marked like galastore's crazymachines bundle but I wouldn't depend on that cause you never know if next time it comes around they decide to mark it and you'd look stupid to complain if they did))

edit- apparently that wasn't quite accurate, it looks like its a max of 25 not 30 for full value but you can hit 30 with pure bundle after , the formula and explanation of how it works and what its meant to accomplish/its purpose is here
http://www.steamgifts.com/forum/Ihcl4/how-were-planning-to-fix-bundle-keys-and-contributor-values-option-1-revised

The first $25 of bundle games you give will count as regular giveaways. Over that, your bundle value won't count for over 20% of your regular giveaways. Giving only bundle games, you contributor value will max out at $30.