This an awesome idea!

I have some observations about what were posted so far:

1. The challenges that @Finalspace posted about remaking old classics is amazing.
2. Challenges could have a format, regarding what expect of gameplay, art style and technical aspects.
3. Regarding what @Finalspace and @Husk said. I think restricting the programming language isn't a good idea, on the other hand, I think having some challenges with "make it in any programming language and framework, but don't make in a game creation system (as Game Maker, Unity, Unreal, etc)". The reason I don't like the first restriction, but I like the second is because the second restriction (any programming language, no game creation systems) allows the developer to improve the understanding of architecture, since there won't be any creation system doing all the backend work. Also, we could learn from each other some nifty architecture tricks, that you can't when using a game creation system.
   • Tldr: no language/paradigm/framework/platform restriction, but sometimes game creation systems restriction
4. I like the example that @Alpha_ProgDes posted.

Here's also two examples of what I'm thinking about:

First example

Quote

PACMAN Challenge!

This is the challenge description. Remember pacman?! Pacman was launched XYZ years ago. Happy birthday, pacman! Your challenge is to make a pacman clone.

Game design requirements

The game must have:

• Start Screen
• Win/Lose Screen
• Graphics for the UI, pacman, items, and ghosts (ie. not just a monochrome rectangle and ball)
• Scoring
• Sound effects
• Music
• Exit (key and screen)

The gameplay must be at least like pacman, but you can make additions.

Art style

The art is limited to 8 colors, even if you make it in 3D (which you can limit using shaders or texture with no light).

Technical restrictions

1. Write in any language and framework (your own, MonoGame, GLFW, SFML, SDL2, etc.)
2. Don't use a game creation system

Deadline

November 30, 2017

Second example

Quote

SUPER MARIO BROS Challenge!

This is the challenge description. Your challenge is to make a mario clone!

Game design requirements

The game must have:

• Start Screen
• Win/Lose Screen
• Graphics for the UI, character, items, and enemies  (ie. not just a monochrome rectangle and ball)
• The character must have 2 states (like with Mario, when you get a mushroom, your character is big, and when hit by an enemy, the character is small)
• 4 enemies with distinct AI
• Scoring
• Sound effects
• Music
• Exit (key and screen)

The gameplay must be at least like Super Mario Bros, but you can make additions.

Art style

• The art must be 2D, but no color or style limitation
• The music must change when the character is big and when is small

Technical restrictions

• Screen must be 256 pixels in height and 180 pixels in width

Deadline

November 30, 2017

Edit:

added "platform" to the list of things that should not be a restriction.

I think @Alpha_ProgDes meant to be a template, but not the challenge itself.

I almost forgot, would be nice to encourage (not obligatory) a small post-mortem. For newbies, it would be an opportunity to hear feedback from more experienced developers, for more experienced developers, would be a nice way to share their nifty tricks with other developers.

About what was said regarding simultaneous challenges:

• The good is only one challenge at a time. Two or more will result, like said before, in unbalanced challenges, less participants, more difficult to share experience, and less interesting.

Now, and idea I had that is quite easy to accomplish:

• One moderator will open the challenge thread (mentioning the author of the idea "this challenge was brought by blabla").
• You can only post your game entry on that thread. No questions (maybe the moderator could open a second thread for questions).
• The reason you can only post your game entry on that thread is that because that thread will be used for voting (with the forum voting system).
• There will be a *HALL-OF-FAME*, a single thread pinned for all the challenges, where the moderator will copy-paste the winner entry there. Using the quote system from the forum (preferably).

* Ignore what is with strike-through, I just saw we are not in Lounge, and anyone can make a new thread.

Edit:

Quote

--The "Make X game" should be a everlasting challenge with NO DEADLINE. Anyone can jump into it and do it when he/she feels like.

In addition to this, the moderator would post something like "the winer is blablabla" in the thread, and people could continue posting in the thread whatever, including games they made later. 

I made a gist with a template, rules examples and a challenge example (pacman):

https://gist.github.com/ferreiradaselva/edf2816e4e80925704ca1e024f5f8530

Any feedback?

I added a bunch of artistic specific rules that i thought that can be useful for people to improve their artist skills, also I removed the technical rules (I still think we should focus more on making the entries with non game-creation systems, thought, for the reasons I listed above and because it's far more easier for the others to analyse the code).

Since anyone can open a new thread here, how do we decide who publishes a new challenge and in what order? I don't mind starting a challenge thread

Edit:

I've written a challenge, can I open a thread for it?

Some mod, could open a pinned thread "Challenge Progress" where people could post their progress, instead of posting in the thread of the challenge itself. It would be nicer to use the challenge thread *only* to post the entries.

I'm not at all clear on what a "challenge" is supposed to be. Is it supposed to be like "Make a clone," or "Create something using theme X", or "implement this particular element of a game using X", or all of the above, or something else?

From what I understand, all the above.

Making clones is good for beginners (and it's fun).