A gamejam is an event where participants try to make a video game from scratch. wikipedia There is a plethora of gamejams happening every day. Look at websites like indiegamejams or the itch.io jam listing and you realize that you could easily do 20 gamejams a day or even more.
While every gamejam is a lot of fun and a great way to get creative, there are surely differences in the jams around. By now I have participated in over 150 of those, so I can give you some insights on criteria for great gamejams and give some recommendations on which jams to join.
So what distinguishes a gamejam from a great gamejajam? What should you consider when joining a jam?
While short events can help you focus and get maximum output with minimum amount of time invested, they can be way more stressful than longer events. The default mode for gamejams is to run for 48 hours on a weekend, which seems like a reasonable compromise.
You should think about how much time you want to invest and then pick an appropriate jam. And while a weekend sounds like a hefty commitment, you do not have to spend the complete time of the jam working on your game. Take some time offscreen, e.g. for a walk. Meet some friends or go to a party. Giving your brain some time to relax is very important and will actually improve your result compared to crunching through a complete weekend.
For shorter jams it is very common that the percentage of time you spend on them is higher, while for longer jams you can take breaks or e.g. only work on your game for some hours on the weekend. E.g. some relaxed jams run for a week or month and you can just work on it on the days where you feel like it.
While there are many online jams, there are also a lot of in-person gamejams. Online jams have a nice relaxed "jam from the couch"-atmosphere. At in-person jams you can meet like-minded people, make some friends and get some direct feedback on your game just by asking the jammer next to you. And for most in-person jams there will be food and drinks provided.
Of course this choice depends strongly on personal preference. Based on where you find yourself on the introvert-extrovert scale you might favor one or the other mode. Speaking from experience: both remote and in-person gamejams provide awesome experiences.
I strongly recommend to go to an in-person event, as jammers are very supportive and meeting them can give a great boost for motivation.
The community is the reason to join a gamejam. You can always work on games alone in your room without any deadline, but having supportive people around you is super helpful and gives a massive boost to your motivation!
There are two aspects here. One is the size of the community. Small communities feel a lot like family, while larger communities will give you way more exposure and options to interact. But of course it is hard to keep up with everything in a discord server with thousands of participants. The second aspect is how the community is run and how that resonates with you. There are some jams that are purely community driven, and there are some jams that are organized by a single person taking all decisions. And of course there is everything in between. While a community driven jam might allow (and sometimes require) more personal engagement, a monolithic jam has a single point of failure and if you happen to disagree with one aspect of the organization, there is little to do about it.
Some jams do offer prizes for winners. Those can range from steam game codes over physical goodies to mentorship offerings or even publishing deals. One of the biggest jams with prizes is the js13k challenge. And if you place top three in a Ludum Dare the word is that publishers will be likely to contact you. Some jams do have a jury and your entry will be judged, while for other events the community will give feedback and ratings. Other jams are just there for the fun and you will get no other reward than finishing your game (which itself is awesome) and people playing it.
You need to decide if you are ok with your game being judged and rated. If there are prizes and winners, there are unfortunately also teams and games who have to take the last place. And be aware that prizes always attract people who are there just to get the prize (especially if it is mentoring or publishing). Which is an a-ok motivation, but some people tend to get angry about that. On the other hand, jams without prizes will be more supportive and less competitive.
There are lots jams about unique specials. While most jams have a specific theme, some jams revolve around a special tool, language or engine. Some take place in a cool location and some are about a specific genre. Some offer a specific type of food and some are in a specific location. Some jams enforce strict technical limitations, like a low screen resolution, a limited file size or a specific color palette.
Joining those rare but special events can be an awesome motivation. If one is around the corner and you have some free time, I definitely recommend them as they spice up the normal gamejam idea quite a bit.
My recommendations for jams are the following: