GOG is giving away four classic oldies and some 'validation'

If there's one thing I've learned from years of reading Garfield, it's that Mondays are bad. This particular Monday is good, however, because on this Monday, GOG is giving away four classic oldies. 

Shadow Warrior Classic Complete, Stargunner, Bio Menace, and Tyrian 2000 aren't the newest games on GOG (or, you know, in general) and the original Shadow Warrior is, well, sort of racist. But if you haven't picked some or all of them up previously, you're not going to beat the price.   

GOG didn't say how long the games will remain free, but it did tease in a follow-up that if the "free stuff" tweet is retweeted 1000 times, "we'll give away some validation." I have no idea what that means but when I find out (it's bound to happen, it's near the 1000 retweets mark already) I'll let you know.

Update: As promised, your validation. I can't decide if I'm let down or not.