It is a sad truth that not every game needs to be ported to every system, particularly when the game doesn't have anything other than the nostalgia factor going for it.
Back in the day, I popped many a quarter into the Altered Beast machine, I spent a lot of time playing it when I got a Sega Genesis, and even played it on a PC as well. It's a game I remember fondly from my past, unfortunately it probably should have stayed there.
I thought the game was the greatest thing since sliced bread. The voices may not have been very good, but they were different and it was excellent side-scrolling beat'em-up fare with a character who changed repeatedly and some weird mythic story going on.
Playing it again now, it strikes me that all my fond feelings for the title stem from playing it in the arcade and that I found the Genesis version somewhat lacking. In the port, it was hard to get your character to do exactly what you wanted--movement felt very stilted and the attacks never quite worked properly (the punch wasn't long enough, the button responded too slowly, the shot was meant to go up and it went straight, etc.). Plus, not that I ever got very fair in the arcade version no matter how many quarters I put in, but the Genesis version was notably shorter.
What we're now getting for the iPhone is, as with the port for the Wii's Virtual Console, the Genesis version of Altered Beast once more. On the iPhone, the game sports all the same faults and issues that the Virtual Console and Genesis versions had. Even if the Genesis version wasn't inferior though, the overarching sad truth of the matter, the thing that it has taken me a long time to accept, is that regardless of how much I may have liked the game years ago, it simply isn't very good in today's world.
As the story goes, Zeus has you rise from your grave to save his daughter, Athena, from the bad guy, Neff. Why Zeus needs a dead guy to do this for him instead of doing it himself, having Athena (she is a god, after all) take an active role in her rescue, or calling on some other god to help is one of those things you shouldn't concern yourself with. You go through the various levels battling all manner of undead thing and can transform yourself into a variety of beasts (perhaps most famously, a werewolf in the opening level) by destroying blue oxen and collecting the spirit balls that eminent from within them. You punch, kick, and jump your way through the levels, getting knocked over repeatedly and listening to some pretty poor synthesized sounds and music.