whatsnewt

A TUI text adventure through what's new in Python 3.15.

You wake up in the Startup Foyer, somewhere inside the interpreter, and work your way to the Release Gate. Along the way there are eighteen puzzles, and every one of them is a real 3.15 feature you have to actually use. You're not just answering boring questions, you're actually writing and running code, in a Python 3.15 interpreter.

Some puzzles require a type checker, and in those cases, answers are verified by pyrefly, which is a dependency for exactly that reason, and the verdict quotes what it says back.

Here's an example of what the scoreboard looks like:

┌─ The Hall of Imports ──────────────────┬─ Progress ─────────────────────────┐
│ A hall the size of a cathedral, stacked│ Score    40 / 375                  │
│ to the vaulting with packages.  The    │ Puzzles  2 / 18                    │
│ moment anyone steps through the door,  │ Sigils   2 / 6                     │
│ every lid in the building flies open at│ Rooms    7 / 15                    │
│ once...                                ├─ Carrying ─────────────────────────┤
│                                        │ * the lazy lantern                 │
│ Puzzle: The packages that open         │ * the frozen seal                  │
│ themselves (PEP 810)                   ├─ Map ──────────────────────────────┤
│                                        │                ?                   │
│ > solve                                │   Crypt   -  Loop↓        ?        │
│                                        │                |                   │
│                                        │     ?       Gardens       ?        │
│                                        │                |                   │
│                                        │   Vault   ->Imports< -  Babel↑     │
│                                        │                |                   │
│                                        │              Foyer        ?        │
└────────────────────────────────────────┴────────────────────────────────────┘

Play the game

The easiest way to run it is directly from PyPI. Ensure you have uv installed and then run this:

$ uvx --python 3.15 whatsnewt

From a git clone there's a shim script which fetches CPython 3.15 if that version isn't installed on your path, creates all the necessary virtual environments, installs all the necessary dependencies, and runs the game as an editable install right where you are:

$ ./play

Useful flags, passed straight through by ./play:

Tab completes at the prompt: verbs first, then whatever the verb can take here -- ex<tab> gives examine, and examine st<tab> finds the staircase if this room has one. Ambiguous prefixes fill in as far as they agree and then show you the choice.

There are many clickable links sprinkled throughout, which can provide clues in the Python 3.15 documentation or various PEPs. Some of the puzzles are tricky or obscure, but you should have enough clues available to get you through the game.

The game works best in a 112x40 terminal or larger, but it adjusts and works in terminals down to 80x24.

On Windows, the puzzle editor shows plain text instead of highlighted code. The highlighting comes from tree-sitter, which has no Windows wheel for Python 3.15 yet, and building it from source needs a C++ compiler (GL#6). If you have one, such as Visual Studio's C++ build tools, you can ask for the highlighting yourself:

> uvx --python 3.15 --with "textual[syntax]" whatsnewt

or, if you installed whatsnewt into a virtual environment, run python -m pip install "textual[syntax]" in that environment.

Yes, there are easter eggs!

It needs Python 3.15

Since almost every puzzle is checked by running your answer against the feature the room explores, you actually need Python 3.15. Pre-release versions are acceptable, but stick to betas or release candidates so you're testing post feature-freeze.

Note that reading your source is part of how answers are checked: most of these puzzles have a boring answer that produces the right value, so the checker looks at how you got there as well as what you got. For example, a nested for loop that flattens correctly is still not what PEP 798 is for.

Commands

There are many commands, which help can explain, but in brief:

• Navigation through the map: north, south, east, west, up, and down
• Interacting with things: look, examine <thing>, take, drop
• Checking status: inventory, map, score
• Game play: save, load, quit
• Puzzlin': solve, hint (cost points!)
• Who made it, and where to report a bug: about

I'll neither confirm nor deny any rumors of easter eggs!

Keys follow Emacs where Emacs has an opinion: ctrl+g aborts whatever puzzle is open, ctrl+h is help, ctrl+l re-shows the room, ctrl+r opens a puzzle — and checks your answer once you are inside it. The function keys still work, and every one of them is a command you can type instead.

Inside the code editor: ctrl+r checks your answer, ctrl+h buys a hint for a point, ctrl+o hands the draft to $EDITOR and takes back whatever you save, and ctrl+g closes the window, keeping your draft for next time.

ctrl+o only suspends the game for editors that need the terminal. If yours opens a window of its own — emacsclient, code --wait, subl -w — the game stays up while you type, and takes the draft back when you save. Set WHATSNEWT_EDITOR_WINDOWED=1 (or =0) if the guess is wrong for yours.

Saving

The game saves itself after anything that changes it, so quitting, closing the terminal or losing the window costs you nothing — including whatever you had half-written in a puzzle editor. It writes to $XDG_STATE_HOME/whatsnewt/, falling back to ~/.local/state/whatsnewt/, rather than the working directory, since ./play deliberately runs from anywhere.

Start it again and it offers to resume your game. Declining doesn't throw it away: the old game is moved to previous-game.json beside it, so a mis-click is recoverable. save <file> and --load FILE still work for games you want to keep by name.

What it covers

Development

The project is managed by Hatch. You can

$ hatch run all

to run the test suite and static analysis checks.

Everything the game teaches is answerable from Doc/whatsnew/3.15.rst.

Feedback is greatly appreciated, especially if you find bugs or inaccuracies in what the game teaches.

Author

whatsnewt is Copyright (C) 2026 Barry Warsaw barry@python.org

Licensed under the terms of the Apache License Version 2.0. See the LICENSE file for details.

The game was largely co-written with Claude, so maybe Barry should be considered a Director or Producer in the music and film sense of the word. The game has been test run by Barry and several prominent Pythonistas.

Project details

• Project home: https://gitlab.com/flufl/whatsnewt
• Report bugs at: https://gitlab.com/flufl/whatsnewt/-/work_items
• Source code: https://gitlab.com/flufl/whatsnewt/-/tree/main
• PyPI: https://pypi.org/project/whatsnewt/
• Changelog: https://gitlab.com/flufl/whatsnewt/-/blob/main/CHANGELOG.md
• License: https://gitlab.com/flufl/whatsnewt/-/blob/main/LICENSE