What GOGs have you purchased "just because" and found that it / they exceeded your expectations?

I've been pleasantly surprised so far by King's Bounty and Gothic II.

Fallout honestly cause I wanted to see what all the fuss was about that game, needless to say I found out.

I've bought a dozen GoGs and haven't played them yet.

But I did get Advent Rising on steam a few years ago. That game was surprisingly good.

Master of Magic is the current one as I haven't played quite a few of the GOGs I've brought. Keep coming back to it day after day :)

i bought a lot of games where i already knew there are classics and still hold up today, but those that reallly surprised me so far are:

Freespace 1+2
I put that source code stuff and that graphic mod on top of it, and it looks just awesome. And even without hose mods those games are really good even today. Its not exactly the same as Wing Commander since that was more about all the fellow pilots and half a movie, but it is as good.

Total Annihilation
So many features that are still in none of any of todays RTS games. Epic doesnt begin to describe the scale of TA.

The Guild
Won it here, and its something else. Its something between an RPG and moneymaking game.

I lose interest in games alot, thats why i haven't played many of the GOGs i've bought. But Gothic for me was a nice surprise, especially after hearing everyone whine about the controls which seemed perfectly fine for me :P

Beyond Good & Evil

Lots of gamers have affirmed that it is a great game. I doubted but eventually I enjoyed it, more than I expected

Giants: Citizen Kabuto

I totally missed this one back in the day. Very funny and has my favorite jetpack evar! I'm normally pretty negative about TPS (vs FPS) but this one is done right.

Well, it wasn't entirely a "just because" but Arcanum is probably the closest for me. I was a huge fan of the first two Fallouts, so when Arcanum (made by some of the same folks) went on sale I asked a few questions & took a chance on it. I wasn't immediately impressed, but I grew to absolutely love it.

One game I completely bought "just because" was The Feeble Files. I wanted it just because it looked like a funny space adventure & it reminded me of the old Space Quest games. I haven't gotten to playing it yet though, so I can't say I was pleasantly surprised by it yet.

Tex Murphy: Under A Killing Moon. Now one of my favorite games.

This is mine.

Tex Murphy, you say?

I do have it on my wishlist... hmm. But I have so many others to play!

Warlords: Battlecry 3 - this one got me for quite a few days (however, I didn't purchase it, I got it from the "give a GOG, get a GOG" thread).
Master of Magic - I don't like the Civilisation games, but maybe because of its setting (and because I love Age of Wonders games), MoM was very entertaining experience for me.

Pretty much this. I thought the controls were good for a change myself and after I really got used to them, they felt better than the standard controls in other games. ;)

Freespace 1+2 - thought it was going to be good, still exceeded expectations.

Actually pretty much the everything that I've bought and tried out but hadn't played before. Freespace 1+2 are the first games that I played to completion though that I hadn't played before.

However, I've still got a lot more to go ... and GOG keeps forcing me to buy more! It's true, they do ... I swear. :P