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Catjam 2026<br>Hosted by andsfw · #catjam2026

22<br>Joined

OverviewCommunity2

Submissions open from 2026-07-04 04:00:00 to 2026-09-08 16:00:00<br>Starts in<br>years

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Make a game (or toy or a zine!? oh my!) with a catlang (concatenative language) or includes a catlang in some way. Doesn't have to be purrfect, doesn't have to be good, just has to exist. Make it with console output. Make it with graphics. Make it with audio if you're feeling bold! Experiment and have fun.

If you need a theme, uuuhhhhhh, hats! Optional, but may that provide some kind of inspiration if needed.

Previous jams: 2025, 2024

What's a Catlang?

A concatenative programming language is a point-free computer programming language in which all expressions are functions, and the concatenation of expressions denotes function composition. Concatenative programming replaces function application, which is common in other programming styles, with function composition as the default way to build subroutines. Concatenative Languages Wiki: https://concatenative.org/wiki/view/Front%20Page Join us on discord: https://discord.gg/Rbre4uHCt5

Rules

No Generative AI : doesn't matter if it's a big name SaaS or a local model. All work done by you (or your team) on your submissions (gamedev, artdev, langdev , etc.) should be made without any AI assistance.If your question about this rule starts with "can I use a [LLM | generative AI model] for...", the answer is "NO". This rule operates in good faith, do not squander it by lying to our face.<br>Also, if you've built a catlang before the jam, this rule applies to its development history. If your catlang was developed with AI assistance of any kind, you will have to make a new one or use someone else's. This includes promotional art and branding for the project. You can, however, remove those and replace it with something you made.<br>Vibecoded catlangs are preemptively excluded. One such example is Slap.

Readymade human-made assets are allowed to be used. Feel free to remix things from Freesound, Wikimedia, the Smithsonian Open Access collection, or other hubs of creative commons and public domain assets. Collage is an art! Have fun with it. Just don't forget to credits your sources and follow whatever terms such as CC-BY-SA.<br>Some prior work on the game itself is also allowed. Framework, engine building, designing, mockups, etc.. You may even dig up some old abandon project. Just don't submit something already finished or nearly done. Again, good faith.<br>Mature anor sexual themes should be appropriately marked.<br>Jumping Off Points<br>Unxtal with Varvara, past entries Polycat, Hexgarden<br>UF built on top of Uxn and Varvara<br>Onion which compiles to Lua, past entries Pop or Be Popped, IWTGAPBTSWSRA&BKTIEI<br>Mirth which compiles to C and has some graphical examples<br>r3 which has native support for SDL2<br>RetroForth (no graphics it seems, but terminal games are 1000% valid) (also you might be able to write some bindings?)<br>Equinox which is a Forth-like language that compiles to Lua like Onion<br>Factor, past entries BitGuessr (Raylib 4.5 bindings)<br>It's also very possible to build your own catlang from scratch in a short time! A good thing to read would be Synopsis of the language Joy, the canonical catlang. Or take inspiration from one of the above languages. Forth or an Uxn-like assembly language would be pretty quick to get up and running. Consider adding many stacks like Mirth or additional auxiliary stacks like Onion. Catlangs are a greenfield with lots to explore.<br>Also, there is even some prior art in bootstrapping Forth in Lua.