This isn’t part of the official Splatterhouse series, it’s a parody of the first game for the NES. The biggest change is the transformation of all characters into super deformed characters, which is probably the first and most obvious clue that this isn’t entirely serious (hence it being called SD Splatterhouse by its fan-translators, since the game never saw a western release). Some of the monsters and whole scenes from the first Splatterhouse are in the game, albeit changed due to the different style. What you can expect in terms of style is a vampire who does the moonwalk, a cutesy variation of the alienburster and similar cutiefied horror cliches.
The gameplay is not the typical beat’n run gameplay from the original, but more in line with typical platformers of that time. You wield an axe to kill enemies, but avoiding them by jumping over them is also an option (something you couldn’t do in the original). It’s a long game, but since it’s more on the easy side, the length doesn’t pose much of a challenge. Despite it’s overly cute look, it’s really fun to play. There’s also a secret ending that implies that this is actually a prequel to the first Splatterhouse, but how canonical these events are is up to debate considering the nature of the game.