The ZX Spectrum version of Poogaboo: La Pulga 2 – the sequel to the classic Bugaboo (The Flea) – was coded by the same guy who created the original (Paco Suárez), so plays similarly, and is also what I’d call an authentic sequel.
Poogaboo was only ever released in Spain – by Opera Soft, in 1991 – so is relatively obscure as Spectrum games go. I’m a big fan of the original Bugaboo, but hadn’t heard of this sequel until recently, so was pleasantly surprised by its existence.