Flatpak 1.12 will be the next major release of the open-source Flatpak system for building, distributing, and running sandboxed desktop applications on GNU/Linux distributions after the Flatpak 1.10 series. It promises several new features like better support for the Steam Linux Runtime mechanism, allowing Steam to launch games with its own container runtime as /usr.
In fact, this new feature allows any subsandbox to have a different /usr and/or /app. Flatpak 1.12 also promises improved support for TUI (text-based user interface) programs like GNU Debugger, a highly performant reimplementation of ostree prune designed specifically for archive-mode repositories, and support for Flatpak instances of the same app-ID to share their /tmp directory, $XDG_RUNTIME_DIR environment variable, as well as /dev/shm directory.