Obviously many of us ended up claiming multiple "Only One" elements, but I imagine we all started from one core "Only One."

For my team's project, the original core "Only One" was
"Only turning in one rotational direction, but in 3D."

I figured it'd be used for a non-euclidian racing game, but as we did a genre-brainstorming exercise with our favorite Only-Ones, someone thought of combining only turning one way with a flight genre game and suddenly the game we made started coming together.

Now our list includes: one rotate direction, one engine left, one engine remains, one attempt to land, a world-war one plane.

What was your team's initial/core "Only One" and how did it evolve?

For our game, https://portrait-prophecies.itch.io/while-the-whole-world-laughs, "only one" is in reference to the protagonist being disjointed from existence by their lack of memories, and their final choice in the story.

My "Only One", was to have only one color in the world. Depending on the current selected color, the properties of the world would change. I wanted to add some more interesting puzzles where you would need to time switching between different colors, but didn't have enough time to figure out a good design and implement it :p

This is a link to my game if anyone is interested in checking it out: https://itch.io/jam/gmtk-2019/rate/461706

Also, apparently my game doesn't even work. I've tested it on Chrome and it seems fine to me. Would appreciate it if anyone can confirm if it's not working for them too. 

Originally my plan was only one colour, which I've stuck to but also I suppose only one screen could count too :)

https://itch.io/jam/gmtk-2019/rate/462582

Only one tower! For a tower defense, that is. Apparently, not very original at all, hahaha, but i tried to take all the juice out of the concept as possible. It's an evil teleporting tower! Just fun. Also loved to make the animations for the towers, the melting and stuff, 

I have played other "Only One Towers" (even with the same name) and it's fascinating to see other people's take on the idea. Seriously, it's like 20 of them out there.

Here is mine! It's kinda really hard, i challenge you to beat it, haha  https://stopsignal.itch.io/only-one-towergmtkjam

i'd also recommend the other ones, seriously! 

https://matheuscunegato.itch.io/towerbag this one has a lovely artstyle, for example, check it out!

I honestly thought back to this super Mario 64 speedrunning video where this dude talked about how to beat the game with the fewest possible A button presses. More specifically how to beat a certain level without pressing a more than once. The fact that there was so much depth in deciding when to press A and what actions were available to you based on whether or not you were still holding it down showed off how versatile Mario 64's movement really was. I went with the idea of being able to press each button only once because I thought that I could take a basic platformer, but force the player to always be considering what actions are available to him, and which buttons he will need to save for the future.

Check my game out here, it's called Full Press and, even though I don't think it's a winner, I think I made a good attempt at exploring the idea.

My only one is my Grandma who died less than a year ago. I did this game about her <3 It's in french but trad is comming !

https://itch.io/jam/gmtk-2019/rate/462187

My game adhered to it's core "only one" theme to a T. Even down to the name of the game. Every weapon you use has only one use before breaking, only one durability. 

For me the first thing that came to mind was "One Shot, One Kill" so I built my entire game around that idea. 

https://bigfraudbigfraud.itch.io/gmtkjam2019

My "Only One" was one leg because I thought it'd be funny to have an fps with a constantly stumbling character, but it's was too disorienting to play so it ended up becoming a third person platformer instead. Because of time, I couldn't really add mechanics that I wanted (like shooting) so I took a different direction ;)

Can't spoil it, if you're interested you can give it a try!

https://itch.io/jam/gmtk-2019/rate/462200

For It's Rude To Point, our team's "only one" was interpreted as "only one finger". With one interactive finger, you would interact with on-screen objects by either grabbing or flicking them. 

We actually stuck very closely to this concept, but instead of just making it a point-and-click sandbox game, we decided to spin it into a series of short action minigames that would all involve the finger in some manner - very similar to WarioWare or Dumb Ways To Die.

It'd be much appreciated if you could give It's Rude To Point a try, and possibly a rating too! It's WebGL-based, so you don't have to download anything to be able to play it (aside from the Unity Web Player plugin).

https://itch.io/jam/gmtk-2019/rate/461113

I did "only one" button where clicking the mouse does multiple different mechanics.  Then, just to be safe, I used "only one" color on top of a black background for the graphics.

For my project I used a few. Only one life. Only one jump. And another "only one" to anyone that makes it through the game (If you finish the game you will understand). I only had about half the time to work on it because I couldn't take time off from my job, but I think I got the theme across pretty good.

This is my first game jam and I made a game called bounce shot: https://itch.io/jam/gmtk-2019/rate/461622
It has one button control, there's one player, one enemy, you technically have one health, and it plays on one screen.

You need to kill the enemy by shooting your bullet at them, and bouncing it off the walls to get around obstacles. You get more points, the more times the bullet bounces before hitting the enemy.

I'd also recommend this game: https://itch.io/jam/gmtk-2019/rate/461470. Lots of fun, and a cool idea.

My "only one" started with only one weapon on a maze...

... then I saw that the weapon could be the player's life as well!

https://itch.io/jam/gmtk-2019/rate/463767

You start in a ghost state, nothing can attack you and you can't attack anyone. When you find/get your life, then you have to sacrifice it to turn surrounding enemies into ghosts. Whenyyou do, you go back to the start, the life stays where you were and you have to find it again, but now there are ghosts that can kill kill you.

For our project A Cat Named Shmup, we did "Only One Bullet".

Since in most shoot 'em ups you just fire an infinite stream of bullets, it provided a really interesting design challenge to only be able to fire one bullet! Our solution was that when your bullet collides with an enemy, the bullet splits into another bullet causing a chain reaction effect.

It's really interesting to see how limitation can drive creativity!

for my game, "Only One" is a shooting game with only one bullet. In my game, the player has only one boomerang and can only throw it once at a time. So they have to think carefully before throw it because they will be vunerable after throw it. Here's the link: https://itch.io/jam/gmtk-2019/rate/46355

Ours was only one platform. We had very good ideas but we went with this one because we figured out we could give the player the control of the platform, and so he'd have to be aware of the movement of both the platform and the character.

In the end, we got a pretty solid game imo. You're a surfer astronaut, and the platform is a hovering surfboard. We came up with some cool mechanics, for example, there are satellites that fire a laser beam that kills the player, but they have a button in the back that the board can press in and the laser turns off. We tried to make a WebGL build, but it didn't work very well, so sadly, you have to download it, but we'd appreciate a lot getting some feedback!

https://itch.io/jam/gmtk-2019/rate/462969