Left arrow key  – left
Right arrow key – right
Space – jump
R – rebind controls
.iso files are full Sortix builds with the game set to launch automatically, and can be run in qemu, VirtualBox, or even real hardware. Sortix is free software and the source code can be examined at /src inside the live environment.
.tix.tar.xz files are for if you have an existing Sortix installation.
Switcher is free software.