You know Rogue. It's what roguelikes are made of.
But you haven't beaten it. Why is that?
Rogue is a difficult, random game. And if you die, that's it, game over.
You can't save your game in most versions of Rogue, so your hours are just lost.†
But CRIU is a magical tool that can checkpoint and restore any Linux process. So why not just dump the process to disk and load it back?
This repo implements a save system for Rogue using Docker. While this is a fun game project, it's also a proof-of-concept for using CRIU on any process that can run in a terminal.
Build it: docker build -t criu-rogue .
Run it: docker run -v $PWD/saves:/saves --privileged -it criu-rogue
Play it: tmux, then rogue
We'll be snapshotting the tmux process tree, which includes rogue.
CRIU can't snapshot it while you're attached, so detach with Ctrl+b, d first.
(Ctrl+b enters the tmux Command Mode, and "d" detaches.)
Run save save1. This will snapshot the tmux process tree to the /saves/save1 dir.
Run load save1. It will restore the tmux process tree from disk.
Then attach to the new tmux session with tmux attach.
Each save is a few megabytes. They will show up in the saves/ subdirectory outside the container.
A save game created in one container will be usable in another container launched from the same OS.
The criu-rogue docker actually works on anything you can run in tmux. For more games, do apt-get install ninvaders or nethack-consolegames. Save and load works the same as above.
Since you can save-state at any instant, it could be great for tool-assisted speedrunning, debugging, or AI development.
Of course, it won't work on network-connected applications; you'd have to snapshot the Internet along with it.
CRIU is a powerful and underused tool. It's not just for games! Caching the state of a whole application could skip many computations. Further, you don't need to modify the source code to use CRIU, or even have it.
See also:
Critmux inspired this project. It connects CRIU's suspend / resume functions to Docker's start and stop features.
Docker Checkpoint is also a thing.
† Some versions of Rogue later added a save feature, but the typical Rogue on Ubuntu / Debian doesn't have one. Technically you can "save", but the save file is deleted when you load it. There's also protection against copying the file: it checks if the inode has changed. This is not easy to circumvent. You'd have to change the source code, hex-edit the save file, or do some low-level hacking on your filesystem. So snapshotting is definitely the way to go.
If you haven't played Rogue before, start with the manual. To learn strategies, consult the tables and tips pages. Or consult the source code itself.
Best of luck on your journey to the Amulet and back.