It seems, like in many film-to-game titles, that they nailed the details while letting the core experience slip.
Firstly, players will notice well-drawn and animated sprites of Ren & Stimpy as they grace the screen in a kind of animated prologue. We see that there's some sort of issue about a pair of yak hooves - Stimpy, supposedly attracted by heir luminescence, is smacked by Ren for trying to pick them up. They belong to the "shaven yak" in the title, obviously.
There are no options in this game. Just START and CONTINUE, which is password activated. So, you start. A cameo by the yak himself gives us the benefit (we think) of playing as either of the two. Anyone over ten years old will soon realise that each character is identical - it's really a cosmetic preference. That said, the lives-remaining system is fairly unique in that you are given three of each character to use. That's fairly progressive for a Master System title, (not even the flogged-to-death series of Asterix and Obelix games thought of that one).
The art direction in this game is fairly spot-on. There's a definite resemblance to R & S themselves, as well as many other minor characters from the series. The colour choice however, seems overly bright, and I'm sure John K. would physically dry-reach if he ever did catch a glimpse; (I once heard that he forbid all primary colours, as well as any secondary colours in all of the episodes he directed). This game however, is rich with them.
Control of the characters is a fairly bland experience. They walk, they jump, and Stimpy spits hairballs while Ren throws toothbrushes - (these are both references to the series). There's moving LOGs, those bloated mosquitos, tree-lobsters, and a few others from the cast in each of the levels. But, you soon notice that the levels have offered all they can within about five minutes. Avoid the chasm, jump the spikes, shoot the skunk, and repeat. It's rather stale gameplay with little variety. Again though, the body count at the end of every level is a nice touch and strangely satisfying as it ticks off the dead - something progressive for it's time?
As with a lot of these older platformers, we are faced with frustratingly difficult boss battles. Various characters from the series, and some that seem purely invented for this title, are up for a showdown every three or four sub-levels. It's one of those tasks that you just know is coming, and, I'm afraid the real battle is between not the characters themselves, but who's holding the bigger health bar (as represented by rubber-nipples here). I hate these sorts of bosses, where they move twice as fast, twice as high, and flash after every hit in a fit of invulnerability. Arghh!
It seems, like in many film-to-game titles, that they nailed the details while letting the core experience slip. There is a good attention to detail (the classic R & S theme is reproduced faithfully), but that attention did not extend to the re-playability of the title. I can't imagine ever having to play this title again - it really does not give any new idea to platforming as we knew it then.
So, it's another Ren & Stimpy title that is missing solid gameplay. At least though they treated the material with respect and loyalty to the program. If they hadn't, this thing would be an insult rather than just plain.