Spent a bit of time with both the arcade Senjou No Ookami and its Famicom port, to see if the actually had some redeemable qualities.
As we already know, the diagonal shots are downright broken, but the game actually becomes playable if you shoot only in the 4 cardinal directions, as the shots come out immediately facing the proper way, as they should. You do lose some of your options, though at times you can make use of the diagonal shots, if you can afford it (where there's some space, or where there's a dangerous target outside the 4-directions range), but you can mostly play the game without them.
Now, if it were the aracade original, you'd die pretty fast, but the FC port has a few quirks that actually makes this feasable.
First, you have a weird hitbox (smaller than the actual sprite), which makes it a bit awkward to pick up items, though this has the fortunate effect of you being able to avoid enemies and bullets more easily than in the arcade original.
Second, though there are an impressive number of enemies and bullets on screen, the game, instead of stopping spawning enemies/bullets when there are already the maximum on-screen, randomly despawns a sprite (either enemy or bullet) to spawn the next one, and so on, meaning you can often get out of sticky situations because of it.
Enemies close to you (those that are already on the screen and sort of follow you around) also tend to not shoot at you at very close range, so you have a bit of leeway to concentrate on the rest of them. This isn't really a hard and fast rule, as eventually they will shoot (later on the subsequent loops, and even as early as stage 4), though it does give make the game seem a bit more fair.
Grenades also take a bit more time to explode, and can throw you off if you're used to the arcade original.
Some things are unique to this version (not present in the arcade game, not sure about the other ports) are random trinkets that appear when you kill some enemies (that give you points), and straircases, that appear when you throw a grenade at specific spots, that lead to a small separate area, that usually has items to collect for points, or POWs (with a few, finite, enemies around) also to be rescued for points. All the staircases I've found where near barricades, where I threw a grenade to kill the soldier taking shelter and it spawned them as well. After exiting this bonus areas, you'll restart at a checkpoint (as you would if you had lost a life).
There are also a new type of enemy that carries a riot shield and throws grenades, and can only be killed with grenades as well (at least I don't remember them from the arcade original).
A few specific areas can, sometimes, be quite hard (especially without the diagonals), like the rocket armed enemies that appear at the start of stage 3 (or 4, I'm not sure now), that may or may not fire a fast flurry of rockets at you, leaving little/no chance of escape. Once again, this isn't hard & fast, and seems to depend on how many other enemies/bullets are on screen, but if you're unlucky, you'll likely lose a life here.
It also has one of the most ridiculous checkpoints I've ever seen (yes, you respawn exactly as shown):
You will die if you fall into these pits, so a single step forward will kill you.
Anyway, it's nowhere near what it could have been with proper aiming mechanics, but it actually becomes playable by restricting your aim this way.