Only one wheel (and horn).  It was a bit of a cop-out.

/jam/gmtk-2019/rate/462253

We had a lot of ideas but the one which got stuck was only having one arrow which you have to pick up again. Or some sort of disc (Tron movie like). But then we had the idea for a top down shooter where you can only use your weapon onces. So, you only have one shot.

Due to time limitations we also only have one level you play in :D

We spend some time on polishing the game to make the play experience better and more fun ;)

If you are interested check it out here /jam/gmtk-2019/rate/460283

We used the theme of ONLY ONE for our character. The game takes place inside his head and he's the only one. He talks to and fights with himself.

If you wanna check it out we'd appreciate it. It's playable in the browser and on Windows with a keyboard.

Link to the game: https://late-panda.itch.io/head-ache

Ours is a 3D Unity game:
You wake up alone in a dark mansion with only one lightbulb.
You cannot leave the place, yet something seems to lurk in the dark. Is it after you? Probably...

Play the game: https://vonrickroll.itch.io/tread-lightly
Rate the game: /jam/gmtk-2019/rate/461550

I used 'only one color'. There's literally a single full-screen color visible at the time. Communication and telegraphing is all done by color-fading and sound design /jam/gmtk-2019/rate/462105

Can 'see'/shoot in only one colour palettte.
...well, strictly it's just harder to see the wrong-coloured entities/bullets, game would be impossible otherwise. And I might have cranked the difficulty up a bit too much, whoops~
Proooobably a bit too loose with the theme, but I couldn't get past the idea once I'd thought of it ^^;
Any critique would be appreciated~

we made a local co-op 2d action game where only player can move at a time so you need to communicate a lot.

My game Echolocation features "only one" of the five senses. You have to navigate puzzles solely using your sense of hearing.

Our "only one" was a only one button with various mechanics.Here is the link:/jam/gmtk-2019/rate/462703

My game is a Metroidvania, but with only one upgrade - a grappling hook. You learn different ways to use it throughout the course of the game, allowing you to access new areas. Here's the link: https://python-b5.itch.io/grapple. I'd appreciate it if anyone played and rated it!

Only One Rectangle with paints)

Simple, colorful platformer)  I would be very grateful if you have a few minutes to play my game)

Game: https://bloodpirat.itch.io/only-one-rectangle
Rate: /jam/gmtk-2019/rate/460625

Only one button. 

You can play it here:

/jam/gmtk-2019/rate/463337

We made the whole game around the "Only One" theme.

• The character looks like number 1
• The goal of the game to turn every 0 block to 1
• In case you hit the block twice you die

https://joysquid.itch.io/run-one

Our idea was to make a 2D Rogue Like where all the values of the game were dictated by only one value, the "life" of the character, in the game is know as the value. So your life it's not only your life, but is also your attack and  your money . But not only these, because the attack, life and  speed of the enemies also scales with the value. It was a really fun experience to balance all these elementes with only one value, so a lot of mathematic equations where use hahahaha. 

If you want to probe the game there it is :  https://rogue-one.itch.io/rogue-one
And the submision page : /jam/gmtk-2019/rate/461305
Any feedback will be really appreciate, thanks :D

I was a bit cheeky with my idea. ;) So there's a whole crowd of 50 friends and the game ends when there is.. ONLY ONE. Would love it if you guys played and left a rating or a comment! 

/jam/gmtk-2019/rate/462221

I did "Only one jump" and then doubled down with "Only one thing that moves". Also the main character is trapped alone on a space station.

There are, incidentally, two endings.

My game is about stopping time for 1 second. If you want, you can try it out, would appreciate it: /jam/gmtk-2019/rate/461675

My Only One was hacking systems using only one button, as opposed to 2 people power-typing on one keyboard, as is tradition.

We decided to create something funny or unusual, and the idea for "Only One" that we came up with was "one shoe" and object throwing game mechanic. What I meant by one shoe is that the main goal of the game is to find a shoe which was lost while wandering inside of an abandoned building. The object throwing mechanic fit the theme quite nicely as well, because the player is able to damage an enemy only once with one object.
Check out the game if you're interested!
/jam/gmtk-2019/rate/463156

For me, worst than death is that ONE TINY MOSQUITO buzzing next to your ear in the middle of the night. Keeping you up from sweet sweet sleep. I really don't know who my game is for... https://mikeyren.itch.io/onlyone