I'm guessing you either found out or gave up by now, but I'll leave this comment here in case a fellow Linux user with the same question comes here : Just download the linux version, extract the archive in any directory, make the file helltaker_lnx.x86_64 executable (on the GUI file manager, just right click the file, select "properties", then go to the "permission" tab and tick the "allow file to be executed" box. ), then execute it by double-clicking it.