I have tried to search for the X series games in the game search page, especially for X Gold. I had no other filters active and was only searching for the game name. But the search acts completely crazy:

First try, input "x": No effect, the browser still displays all 27 pages of games as the result.
Next try, input "x:": No results found.
Next try, input "x " (x plus space): Again all games are displayed (27 pages).

What now?

Other idea, I try to search for X Gold only, input "gold": Finally the filter does anything, but the first hit it displays is Xenonauts? Where's the "gold" in that name? It also lists Clarc, another "hit" which does not contain the search string. Two pages as the result of the search, not really what I want because I have to search the game in the list myself. But at least it lists X: Gold at all.

Next try, now that I know how X: Gold is spelled correctly, input "X: Gold": No changes, it still displays 2 result pages, including Xenonauts and Clarc.
Another try, skipping the space, input "X:Gold": Still no changes, same result list as before.
Ok, how about skipping the colon too, input "XGold": No results found.

Is my browser doing stupid things or is the search broken? Any idea how to search "correctly" for X: Gold? Or better a search string which lists all the X series games without listing (a lot of) other games?

Search for "ego". The search string also checks developer and publisher (like Xenonauts' Goldhawk Interactive), as well as the genres of a game. Weird, but that's how it works.

Nahh.. your browser is fine. I also tried it and it is difficult to search for X series. Maybe something to do with the search algorithm ? GOG web team should know about this.

I found X: Gold using "Gold" keyword but it is on the 8th row.. GOG needs to improve it. Maybe options for advanced filtering in search. Especially with their current growing catalog.

Ah, that's where all the "false" positives come from. Good to know, but that doesn't make the search easier. Is the search behavior explained somewhere? (Not that I really expect that, but you never know. :P)

I clearly would prefer either a plain string search, some kind of keyword search (like "title:abc publisher:xyz") or even a regular expressions search.

Edit: Why does the text search also look at fields which are separate search options on the page like the game genre? That doesn't make much sense to me and only complicates things.

Another fail: Searching for "F-117A NIGHTHAWK STEALTH FIGHTER 2.0"

I thought the shortest unique string to find the game could be "117". Wrong! No results found.
Even searching for "11" or "17" does not find the game.

Ok, it's broken. :P

(It's not a problem in this case as I can find the game when I search for "f-117" or "nighthawk", but it also should find the game when I search for "117" only.)

You wouldn't find anything when searching for "hawk either, but "nighth" would work perfectly. You may cut off the end of the "words" you're searching for, but not the beginning, and since there is no whitespace in "F-117A", it's treated as a single "word" so you'll find it if you search for "f-" or "f-1", but not "17A" or "117".

Also, single-character searches don't work. At all. And strings are split and trimmed before performing the search so adding spaces at the end or beginning of the search makes no effect and each space-separated word is search for independently but all must match the same piece of data (searching for "black torment" will not find you Planescape: Torment by Black Isle as one word matches the developer and the other matches the title, searching for "torm plan" will work though).

Oh, and, yeah, some characters are special, like " : ", " ' ", " + ", and " , " in that they count (but don't match anything) if the rest of the word is shorter than 2 characters, and don't do anything at all if the word is longer.

You could try MaGog.

Any of the following should work:
- x gold
- x2 the
- x3:
and my favourite:
- ^x: | ^x2 | ^x3

Here is the last one:
[url=http://www.an-ovel.com/cgi-bin/magog.cgi?ver=644&scp=gspur&dsp=ipgfsorlcmbahTP&ord=&flt=tcs~%5Ex%3A+%7C+%5Ex2+%7C+%5Ex3~&opt=]http://www.an-ovel.com/cgi-bin/magog.cgi?ver=644&scp=gspur&dsp=ipgfsorlcmbahTP&ord=&flt=tcs~^x:+|+^x2+|+^x3~&opt=[/url]

That explains some of the behavior. Thanks! And that's the part where I'm getting confused. When a search term contains only one letter it's ignored. When it contains one letter and such a special character it's not ignored and leads to no results. When a search term contains one letter and a special character and there is more than one search term it's ignored again:
- "x" finds all games ("x" is ignored)
- "x:" is neither used nor ignored, the search just displays no results
- "x: gold" searches for "gold" only ("x:" is ignored)

In longer search terms these special characters are apparently treated as search term separators:
- "x:gold" searches for "gold" only ("x:" is ignored)
- "xy:gold" seems to search for "xy" and "gold" which leads to no results
- "settlers:gold" seems to search for "settlers" and "gold"

But then again:
- "x:g" "x" and "g" are neither used nor ignored, the search just displays no results

That's some quite confusing behavior, regular expressions would have been much easier. :P And once again MaGog has the better implementation for a feature. ;) To use that search I unfortunately would have to know that the X series games are noted with a colon after the X part of the name which I only remembered as I saw the search results. But at least a search for "^x" limits the result to an acceptable number of games. :)

So the MaGog search has some minimal support for regular expressions?
(The regex I would have tried for the X series games - "^x[^a-z]" - seems not to be supported though.)

BTW: Is there any way to switch off the downloadable files section in the MaGog results? I have tried to switch off any option, but it's still there. It takes a lot of space and is not of much interest for me.
An option to switch off the age requirements in the list also would be nice. But as these do not take that much space it's of lower priority.

MaGog's primary design is not to confuse people who don't know anything about regex. Therefore, any character that can normally be found in some game titles is assumed not to be regex. For example, [ or ] or ( or ) or . or ?. Which is why your regex didn't work.

Only if a character is not really expected to appear in a game title is it treated as regex. Currently, there are three such, I believe: ^ and | and $. And I'm not really sure about $. I may end up changing it if a game appears with it in the title. I have never used it, whereas ^ and | I do use from time to time. Every column or row can be hidden. Just check off the relevant checkbox under Display:
Age Reqs is rightmost on the second row
Downloadable Files is rightmost on the third row.

A fine example of why the letter X is the most overused letter in the English language. Thank pop culture for that nonsense. If we could just round up X, G, and YOLO, toss 'em all into a blast furnace... ah, then we'd be making progress.

'Egosoft' shows all games by them but then you would need to know the name of the the developer of the X games, not a given if you are new to them.

A + + for telling about how the game search works as it has had me consternated several times.

No problem. It's already good to know about ^ and |, which is enough for most cases. Sorry, my fault! Because of the limited width of my browser I did not see the last column of options and somehow have ignored the scrollbar at the bottom ...

Annoying and stupid behaviour, indeed.

I would guess that values stored in the index are determined by the regex \w\w+ (two characters or longer strings of a-zA-Z0-9), but that the preparation process for the search is something akin to this:

1) cut strings into parts fitting (\b\w\S+?) - A: "x:gold" becomes the array ["x:", "gold"], B: "gold:x" becomes ["gold:", "x"], C: "x2: the threat" becomes ["x2:", "the", "threat"], D: "x:" becomes ["x:"]
2) remove strings shorter than 2 characters - search B ["gold:", "x"] becomes ["gold:"]
3) for strings longer than 2 characters, trim off invalid characters - search B ["gold:"] becomes ["gold"], C ["x2:", "the", "threat"] becomes ["x2", "the", "threat"]
4) if search contains valid strings, remove invalid strings - ["x:", "gold"] becomes ["gold"]
5) perform search - search A and B finds everything with "gold" at the start of any stored "word", C finds anything with those strings at the start of words for the same piece of information (ie. X2: The Threat, which has three words stored for its title: "x2", "the", and "threat"), D won't find anything because "x:" isn't stored.