Space Invaders does have surprisingly few *official* ports at least. It's just one of the most cloned games ever(probably).
Konami's Scramble is a bit similar, lot's of unofficial conversions on platforms of the 80's, but the sequel Super Cobra has more official ports, some on rather exotic platforms:
Atari 5200 / Atari 800 (seem to be the same).
Casio PV 1000
Casio PV 2000
Odyssey 2. Only scrolls when reaching the edge of the screen.
Not pictured: Playstation version in Konami's Arcade Gallery (hangs at logo, could be just my image though) and PC-6001 cartridge port (afaik no public dump). In fact, none of the Konami ports for that platform (6 total) seem to be available.