Shalandir just means not many giveaways for this title show up :)

Random as in, most of the time games given away here are currently in a bundle somewhere or have been in a bundle in the past. This one sticks out.
Rare as in, it's almost never given away, so it's a rare treat, so to speak.

Trading generally sucks unless you're experienced enough to know what you're doing, and it's not worth becoming experienced unless you plan on trading a lot.

Dunno about the other game.

The game you linked seems rare enough too. And very interesting as well. Added it to my WL! ^_^ Would make a nice future giveaway.
And Vercinger is right about what rare means on SG means. Most titles given away have been bundled or if not are usually AAA games like Fallout 4. Not many indie or somewhat unknown titles being given away.