In case that you are running a non-Debian based Linux distribution (where a .deb file cannot be installed). There is an alternative for other distributions, for example on Fedora you can double-click a .deb file to open the file content, and extract the data.tar.xz file inside which includes the usr/bin and usr/share directories. You can uncompress the content in any directory and run usr/bin/aseprite, it will act just like a portable program (we take special care to depend only on a minimal set of system libraries like libc and X11, so it should run on most of x86 or x64 distributions).