This thread is about obscurity. Even more so than normal. This is dedicated to those games that you're pretty sure you've only heard of.

Gravity Well
This is one that I played back before it had graphics. It's an action-strategy game where your goal is to land on all the circles and defend them until they're your circles.

The Adventures of Microman
http://www.mobygames.com/game/adventures-of-microman]It's a smoothly animated platformer made using a toolkit.
This was pretty amazing for Windows 3.11[/url]

Critical Mass
I played this game before it had polygons. It's a hybrid of turn based command and real time action. Neat!

Tumblebugs
This one is really, really obscure. Here's a screenshot! It's a lot like Atari's Combat.

Not really a rare game but I spent quite some time to find this one:
Patton vs. Rommel

I LOOOOOOOOOOOVE this game when I was young. :-P

Nice topic.

Only game I can think of right now is Risky Woods. It's a little known action side scroller from early 90's published by EA. I just love the way the game looks.

Longplay of Amiga version

If I take that thread title literally, I can't think of any. But I used to play a cute trilogy of simple arcade shareware games that isn't that well known, I think, called Gargoyle Medieval Pack (1995), consisting of , [url=https://www.youtube.com/watch?v=BIAJSZAnqss]Gargoyle Mania (my favorite), and Gargoyle Revenge. Still, it wasn't me who made these gameplay videos, so ... ;)

The Flight Simulator on ZX81

or

The Flight Simulator Spectrum edition. Me and my dad spend months transposing the code from the ZX81 onto the Spectrum and then making it work.

Centauri Alliance, though not until a long time after release. It can be described as Bard's Tale in space.

The game does have a few issues, unfortunately, like the fact that the interface (particularly targeting during combat) is rather slow and clunky, and the fact that there are some significant bugs in the game. For example, psionic items use the wrong memory location for their charge count (so using one can have strange effects, like changing the power used by another item to something entirely different), and the item that is supposed to let you use psionic powers in anti-psionic areas doesn't work in battle.

Also, the game had no DOS release, and was only released late in the life of the 8-bit computers it ran on.

Slightly less obscure (but available on GOG, though I actually played it through some RPG collection that was released on a bunch of CD-ROMs) is Dragon Wars, which is often cited as the successor to the Bard's Tale series, but is actually quite different from a design perspective; it's significantly less linear, it uses a classless growth system, your HP isn't expected to increase much during the game, and enemies don't drop items, for starters. I think you mean "you're pretty sure only you've heard of". Word order *does* matter sometimes.

There was this board game I made myself.... that must be the only one I can be sure noone else ever played.

There are lots of games I have heard of but not played...

The arcade game I played in Georgetown (no, another Georgetown) in the early 90s.

It had a side view of a humanoid character (maybe in a space suit - there was a time limit that was perhaps styled as remaining oxygen) walking through a level consisting of no more than two platforms. The character was controlled by moving the joystick left and right. There were perhaps other controls on the cabinet (e.g. buttons), but they weren't required for the game.

The first level was two platforms and kinda T-shaped pinkish presses. Those above the upper platform had enough space between every two of them to stand safely, but two on the lower platform (after I walked to the right and fell or perhaps descended a ladder down) were right next to each other and moved slightly out of sync.

The second level I remember as being more orange-blueish. It had disappearing and reappearing elegant arched bridges, and ugly frog faces, about the size of the character, moving up and down. I think all bridges appeared and reappeared simultaneously. The lower platform had two bridges on both sides of a single-width span of solid floor with a frog face on it. That's where I got killed.

I think there was also a level with a stair-shaped sawtooth triangle of solid floor to the left, and horizontal colored rays from the right side of the screen were going on and off, striking the stairs. Probably some of the rays were deadly, but I couldn't figure out which were which from watching people.

And that's all I remember.

Some Chuck Norris game on a cassette tape computer, with logs you had to go over or under, and of course hooligans to beat up.

These don't quite qualify with the spirit of the thread since I have seen each one mentioned here. But mentioned only once that I recall:

Lightspeed, a space combat and trading game from, um, late 80s? Something like that. I utterly sucked at it.

D/Generation. I'm really fuzzy on the details. Future or sci-fi, maybe an action puzzle game? Think you had to puzzle your way through rooms that had various devices set up to kill you, and you had to figure out how to avoid setting them off or something like that. That description is probably not right... Another community member did a remake titled E/Generation, so try a search here and you can find a link to the remake.

Got a third one but I'll have to find it on MobyGames before posting.

I played a lot of an RPG called "Fountain of Dreams" that EA released as a sort of spiritual sequel to Wasteland back in 1990. It really wasn't that good but I loved it as it was my 1st PC game.

I have never met anyone else who has even heard of it!

Iron Helix - sci fi game where you control drones and try to prevent a warship from starting a ... well ... war. It came in a pack with other sci fi games, including the Star Controls.

Intro video: https://www.youtube.com/watch?v=HzRxocI2uAM

Lovely topic!

Commodore 64 Uuno Muuttaa Maalle
Commodore 64 The new Zealand Story
Commodore 64 Fred
Commodore 64 Lode runner
Commodore 64 Beyond the Ice Palace

NES The Guardian legend
NES Tecmo CUp

PC Mega man X3, X4

Uhm, the topic is about games you think only you played, not "list some classics everybody knows and likes" Especially those NES games are all really well known.
If you wanna say a rare NES games, pick something like Ike Ike! Nekketsu Hockey-bu: Subete Koronde Dairantō which barely anybody outside Japan even knows.

I could probably easily list some german computer games like Das Magazin, Das Amt, Software Manager which aren't even that well known here in Germany, let alone outside that country.