...and then realized you are probably the only person in the whole world playing that game right now?

Sometimes, like with Centauri Alliance. (Ever heard of that game? If you have, was it from a post of mine?)

Edit: s/Allinance/Alliance

The whole world is a pretty big place.
So, how would you come to the realization, that you're the only one playing said game right now?

Yea, Anthem ... not so old though... but maybe a bit obscure

There's an old obscure game I was trying to find a while ago but I can't remember its name and nobody seems to know it. :(

That happens a lot with old arcade games I used to play as a kid, seeing some obscure coin op in some place and never seeing it again.

I found a couple of them in MAME, but there is still at least two old arcade games I recall playing (one as in Linnanmäki amusement park, the other was in Särkänniemi amusement park, both probably somewhere in the early 80s).

For instance the one in Linnanmäki was some kind of platformer where you advance from left to right. I don't think the screen scrolled, but the screen would switch to a new one when you reached the right edge of the screen.

I think there was some kind of witch following you from the left which was the reason you had to make haste and not stand around. I recall there was quite a lot of blue and violet color on the screen (not very bright colors), and what was noticeable was that the screen itself was quite small, much smaller than in most arcade cabinets. And the screen was in an upright position IIRC.

The Särkänniemi game was some kind of pseudo-3D penguin game on some glacier, not the one where you crush enemies with ice cubes (name escaped me, but I've already found that game in MAME). I guess that should be rather easy to find, just list all penguin coin op games from the earl-ish 80s or so.

EDIT: Screwed up, the penguin game was indeed "Pengo" where you crush the enemies with ice cubes. The "pseudo-3D" glacier scene was apparently only its intro animation, not the actual gameplay. Oh well, one down. Still to find that platformer.

https://www.youtube.com/watch?v=6q3bNHvj92c

What I want to find is a PC first person shooter.. probably freeware, possibly open source, probably a solo project or made by a few guys as a hobby, and I think I played it in the early-to-mid 2000s. Simple 3D graphics of the late 90s / early 2000s hardware accelerated era. "Modern" in terms of setting; urban, industrial, military complexes. I *think* the player is like some sort of special forces or swat guy, there might have been AI teammates. Not sure if the enemies were terrorist or military or what, could've been both. I don't think there was music. There might have been a few simple sounds (gunshots? maybe footsteps?) but overall it was rather silent. I could've sworn there's an X in the game's name (or it was just called X) but I could be totally wrong about this. I have no idea where I got the game from but probably downloaded from the internet somewhere. Dunno if there was any story (and if there was any, that's not what I played it for).

Yeah I've asked around in a few places and nobody knows this one. And whenever I ask, a bunch of people show up to recommend well known commercial first person shooters that everyone knows *sigh*,

Not really. But I have wondered if I'm the only gaijin to have completed Wizardry Chronicle.

Does it have an english translation?

Sometimes it feels like that, like when I was playing the DS remakes of SaGa 2 and 3 (no translation patches, as I was playing the retail cart on a Nintendo DS Lite), or Game Center CX 2 (though there's an FAQ that gives you the steps to completing the text adventure; not particularly fun to follow then, but gets you to the next game if your Japanese isn't good enough for that sort of game).

By the way, how is Wizardry Chronicle? Does it offer any interesting mechanics?

(Also, have you played Wizardry: Labyrinth of Lost Souls and Elminage Gothic? Both are games of this type that are available on GOG, and the latter is actually really good and really long, though also really hard at times (to the point of making Wizardry 1 look easy).) Apparently, yes.

On the other hand, I've played part of Wizardry DIMGUIL, and that game does not have an English translation.
(Interestingly enough, there is one puzzle throughout the game that involves deciphering glyphs, and it turns out that this particular puzzle is in English.)

Yes.
http://www.romhacking.net/translations/2321/

That would be Z.A.R. (Zone of Artificial Resources)

Surprisingly, it's on Steam but without the mission pack.

https://store.steampowered.com/app/351820/ZAR/

I played that from ISOZone (RIP) and really liked it for some reason. Would love to see it here. Made by the same people who later made IL-2 Sturmovik, a game which is here on GOG, the door for that to happen is already open. Just need to hand out the invite. Get on it GOG :P.

As I love the hobby-dev scene, yes. Very often. There are a couple of old (german) forums where people share their games, mostly point-and-click adventures, to a very small community. And it's just some kind of weird joy to play those silly mostly unpolished games made by people with a real passion for making games instead of money. :)

One of my favorite, but less obscure ones, which I play every know and then is called "Alühn". Unfortunatly it's not available in English, as far as I know. The creator once proudly stated that the game got around 1500 downloads (10 years ago) so chances are very high that I'm the only one playing it, whenever I play it ^^"

So this game has many names depending on where you live:

[PAL] - Snowboard Racer
[NTSC] - Snowbarding
[NTSC-J] - Simple 1500 Series Vol. 27 - The Snowboard

Most people will tell you it's a bad snowboarding game because it's just you all alone going down the hill from point A to point B but that's what make this game so good to me. I find it so relaxing, you have that old school techno music playing in the background and the sound of snow being crushed by your snowboard, every time I play this game it's like my brain is getting disconnected.

This budget game release for the PlayStation 1 is oddly satisfying to me, I can't explain it. I guess in a way this game feels like "ASMR" to me, if you know what that is. Hopefully I'm not the only one feeling like this but I'm yet to find anyone who have heard about this game in the first place lol.

Never, but I probably will next time. Though the only game I can think of that might qualify one day is Montezuma's Revenge