Fan remake
Space Invaders: Invaders Possibly
by Shinobi · Shooter
Space Invaders remake.
Unconfirmed: 'Invaders!... possibly from space!' exists on Game Jolt (https://gamejolt.com/games/invaders-possibly-from-space/2388, by Leylo / Octa Studios), but nothing ties it to 'Shinobi'.
Built upon Space Invaders (1978).