Our team did a visual novel about Social Anxiety where you are only capable of talking to people only once. Went smooth and ended up better than I expect. The team was great and I had tons of fun Voice acting.

https://itch.io/jam/gmtk-2019/rate/463328

For mine the intention was Only One Jump, but I ended up having Only One Screen (per level) and Only One Platform https://itch.io/jam/gmtk-2019/rate/460806

In the past I've been guilty of entering jams with an idea in mind and then altering it to fit the theme, but this time this time my whole idea came purely from the theme. I guess that makes it a good theme 😁

My game is Broken Robot and the only one at the base of the game is that the game is a puzzle platformer where you can only press each direction one time per level. There are other "Only Ones" in the game, but at the core it is the controls that I made the game around

https://itch.io/jam/gmtk-2019/rate/462219

Our game is an 2D action/survival game in only one room. But real the "Only One" of this game is theColor :)
https://becher.itch.io/ligth-them-up
Have fun ;)

There was only one door in the original idea. But then one room appeared... then one minute... one nightmare.... =D

https://itch.io/jam/gmtk-2019/rate/462518

https://itch.io/jam/gmtk-2019/rate/461964 For my game, it was Only One Dimension. There seem to be lot of entries in this theme though, :)

Mine has many "only one things" but has something I didn't find in any other: 2 players. The first ide was having only 1 unit.That's why I called it "One Man War" I latter added a couple more only ones:

You also only mine one resource (wood) 

You have only one building

You have only one goal, destroy your enemies 

https://aleconde98.itch.io/one-man-war

https://itch.io/jam/gmtk-2019/rate/459177 Only one button for us (mouse button), and only one..something else (that one you'll have to play a few seconds to see).

For our game "Only One" was only "One Arrow", that was it. That is the core "Only one" at Unusago. Here is the link if you guys might want to take a look at it: https://itch.io/jam/gmtk-2019/rate/461869

Our game, "1Minute" has several (ironically) only one elements, with better or worse execution.

The original premise for our project was to use one button and make a rhythm game with it. In the end after brainstorming we ended up making a game where you type using a telegraph.

The character is alone on his room. He has one arm. He has a telegraph and a morse code manual, but can only use one at a time. The color palette is centered around one tone. The music you hear while playing is designed around one note and uses only C for the melody. The premise is kinda based on WW1, but we opted for using an aseptic war, with ni real bands or anything.

Ah, also, you have to send one message and have one minute to do it. If you do so, you stop a chemical bomb from being dropped on your country.

My friend and I'sproject was originally  conceived as a "single-stick" shooter (a take on twin stick shooters) with only one stick and one projectile. At first we imagined the player as an archer that would move themselves by firing arrows, but that didn't make a whole lot of sense. We ended up adopting a sci-fi aesthetic, so the idea of moving the character with the projectile's recoil was on the page again. As we built, more and more elements fell nicely into the "Only One" theme. We have one persistent boss enemy, one stage, one life, etc.

My game: Safe Place. A platformer where you only get to attack once per room.

https://itch.io/jam/gmtk-2019/rate/462235

For me the "only one" means, that only one specific side of your dice will grant you access to the next level.

https://itch.io/jam/gmtk-2019/rate/462667 

Title says it all!

Our game is based in a Submarine around the fact that you only have a single system active at a time! Plays around the concept of Minimal Information!

Comments, feedback and ratings appreciated!

https://kaiskii.itch.io/help-im-stuck-in-a-submarine

We went for "Only One" pilot in a fleet of a thousand ships.

Then we added "OnlyOne" Enemy.

The ships that have no pilot can only do very basic actions like fire blindly, drop EMP or flee. the piloted ship can order those actions to nearby ships.

The enemy is a planet like ships that you have to "dig" to reach the core and kill.

The game is called OneOnOnes : https://itch.io/jam/gmtk-2019/rate/463229

Well, I have many "only ones":
- the original is: only one button (LMB)
- the others: only one type of weapon, only one type of enemy, only one level (but these are not intentional, just the consequences of the time limit :D )

No Exit: https://itch.io/jam/gmtk-2019/rate/431948

One button fast paced plat-former, one direction, one sprite, one background, addictive swing mechanics,  cool graphics and  sick beats and rage enduing feature.   

1 button, 1 sprite, 1 enemy/boss. All those things where mentioned in the opening video, so I feel kinda uncreative. -.- Turned out ok though I think.  https://sleeper-games.itch.io/mech-revenant-input-one

“Together as one” I wanted to play with the idea of “one” without it being a singular thing. In my instance a flock of bird coming together. 

https://pitman.itch.io/just-pidgeon

my only one was to have only one room. not very creative, i know, but i think the main mechanic of attracting and repelling only one of the colours could have made a pretty entertaining game: black and white

(could have made because i haven't figured it out how to implement the main mechanic unfortunately)