Space Invaders

Most clones of popular arcade games change the names of the original games at least slightly, but nope, this game straight-up calls itself Space Invaders. And despite being made nearly 20 years after the original arcade game, this game is inferior in several ways. It mostly uses text (those blockers may not be, or could be edited characters?) so you're shooting color-cycling Omega symbols (aka ZZT lions) in a flickering QuickBasic-enduced nightmare. I tried various DOSBox cycle settings and in-game speed numbers but never found one that felt right without a bunch of flickering.

This is the same game as Space Invaders, which has the full page.