OpenTyrian is a port of the DOS shoot-em-up Tyrian. Tyrian is an arcade-style vertical scrolling shooter. The story is set in 20,031 where you play as Trent Hawkins, a skilled fighter-pilot employed to fight Microsol and save the galaxy. This port is done by ZX-81.

Release notes:

Here is an optimised build of OpenTyrian that plays full speed with sound. This archive ONLY contains the executable: opentyrian.dge, please overwrite your old tyrian executable or get the datafiles if you do not have them

http://sweetlilmre.blogspot.com/2010/07/dingux-opentyrian-release.html