Strike Suit Zero: Director's Cut, but then again, that just came out. That one is followed by Divinity: Dragon Commander (not surprised, since it's normally a rather expensive game), Luftrausers (still a new release) and Kingdom: The Far Reaches (not surprised, because...well, it seems like a poor Dragon's Lair clone).

Risen 2 Dark Waters is at the bottom for me. Haven't played it yet either.

It's possible owning the Gold edition or similar for other games might flag the base game and separate DLC packages as being owned also, to avoid buying both by mistake, but with the sale statistic going to the actual purchase. I don't think I own any games that would be in that situation to check though. Risen 2, Dragon Commander, Strike Suit Zero, Omerta, and a few others with DLC might though.

My Bottom 10 are :

FLATOUT 2
RACE DRIVER: GRID
THE BANNER SAGA
DRACULA 4+5
FULL SPECTRUM WARRIOR: TEN HAMMERS
Shadowgrounds
Sherlock Holmes: Secret of the Silver Earring
Age of Wonders 3 - Deluxe Edition
Consortium: Master Edition, The
Unholy Heights

Interesting how there are quite a few indie games in the bottom 50 best sellers generally speaking........

In reverse order:
Edna & Harvey: The Breakout
Strike Suit Zero: Director's Cut
Risen 2: Dark Waters
Chronology
Strike Suit Zero: Director's Cut - again? GOGbug?
Risen 2: Dark Waters - same bug
Chronology - yupp, definitely a bug
Pinball World
creamer 4x4 (- hmm it seems I've forgot an S... but I do thing Creamer 4x4 is a much more fascinating title...)

Unless the list is lying to me, it looks like my bottom game is Lone Survivor: The Director's Cut.

My review after I had finished the game (source: http://www.gog.com/forum/general/games_finished_in_2013/post1235):

Now, I'm not a graphics whore, not by any stretch of the word, but at first I thought this game might be a little bit too artistic even for me with its pixelated, mosaic art style, because it made text hard to read and background objects hard to identify, especially since the resolution was very low too. Eventually I got used to the style, but would've still preferred at least a little bit clearer graphics. That was not the biggest issue I had with the game, though: since it's a horror game, I would've expected it to be at least a little bit scary. Maybe it's because of the art style, I don't know: nevertheless this game was really disappointing in the horror department. I also didn't get the story, pretty much at all. Was my character just plain crazy? The ending came abruptly and didn't conclude anything, imo. Perhaps it has something to do with my stats (blue ending, mental health... F-), but I would've still liked at least some explanations to everything. Oh well...overall I felt the game's truly nothing but a poor man's Silent Hill: it blatantly copied lots of stuff from the series, but failed hard to be as engaging and good. It's as if the devs purposefully challenged themselves to create a Silent Hill -like experience, but for the Game Boy Color. I'm sorry, but for me that simply doesn't work and feels like an impossible idea from the start. One thing I liked about though, was the music. It was really well done throughout the game. That's about it though.

So, it probably deserves to be that low on the list (at least in my opinion!) I've seen many reviews that disagree with mine though, so... tastes may differ.

Mine is Hitman: Contracts.

I was quite surprised to see that title as my lowest selling title on my list. However there was 90+ games between hitman contracts and the freebie games at the botton of the list.

Haha! I'm glad I wasn't the only one!

Oh man, the amount of time I spent on OMF was the ridiculousness! I still think that it holds up as one of the best, if not THE best PC exclusive fighting games of ALL TIME. A record I'm sure it'll still hold, due to no one really releasing fighting games specifically for PC these days.

My "Top" 5 games are:
5. Escape Goat
4. Corsairs Gold
3. Worms Forts: Under Siege
2. Journey to the Center of the Earth
1. Sherlock Holmes: Secret of the Silver Earring

Yes! the keyboard control scheme perfect. Maybe that's the reason I never got into other fighting games.

Harvester... but was almost Balls of Steel. Really interesting to see what the low tier games actually are.

There are some things to consider with this whole idea of "top selling" games also, such as:

1) What timeframe does it cover? Is it "all time since the game appeared in the catalogue", "the last 12 months", "the last month", "the last week" or some other timeframe?

2) Games that are currently on sale or have been on sale sometime within the timeframe the statistics apply to will most likely experience higher number of unit sales than games that were not on sale during the same time period and thus will be more popular than those games. In this case the games which haven't been on sale the longest will be more likely to be closer to the bottom of the list.

3) Other factors such as whether the game is a new release in the catalogue or has been around for 5 years are likely to determine the current popularity trend of a given game title.

4) Has the game been on sale somewhere outside of GOG or in one of the many Steam bundles anytime recently?

I bring this up because some people are surprised to find a certain game they really like or think should be very popular to be lower on the list than they think it should be. I believe the only explanation that makes any sense for this phenomenon is that we simply do not have any idea how algorithm that determines the top-sellers popularity works and over what particular time frame and so everyone is going to make different conscious or unconscious assumptions about that which cause us to be surprised to find a game less popular than we think it is. If we actually knew the algorithm precisely however I'm sure that we could make perfect sense out of it and out of what "top seller" really actually means than what we all individually think it means at any given instant in time. ;o)

Whenever there is a big sale on, one or more of the games in the sale flies to the top of the top-sellers list, often a number of of them. This suggests to me that it is not a "since the beginning of time, total game sales volume" statistic that indicates the games that sold the most copies cumulatively since GOG.com came to exist, but that it measures popularity over a much smaller time window of perhaps the last 1/2/4/6/8 weeks or so, possibly using a moving average or exponential moving average to smooth out the stats over time, the latter giving higher weight to more recent sales numbers.

It would be very interesting if someone at GOG in the know would be kind enough to give us the actual algorithm or even a simplified explanation of how it works and the timeframe. Just for curiousity sake as it doesn't really matter much in terms of influencing game purchases IMHO.

Worst selling game I own, but haven't played:

Tzar: The Burden of the Crown: It was a gem promo for a ridiculously low price, and a true Good Old Game, circa 2000. I'm not much of a strategy / wargamer, but this game has an ardent and vocal cult fanbase so for $1.70 (or whatever I paid for it) I figured what the hell. Maybe one day I'll get around to it.

* * *

Postmortem: Is next up the "worst-selling" list. I actually don't own it on GOG because I bought it at DotEmu, along with several others available there before they ever were here, all of which just happen to be on sale this weekend.

I've played it and it's a solid adventure game. It kept me engaged. I'm not big on the genre, but I enjoyed it and its spiritual sequel Still Life as much as, say, The Longest Journey.

The lowest I've actually played is Consortium which I've enjoyed a lot - go and check it out!

The lowest I've bought is "Journey of a roach". (I don't count Edna)