Meh.
I've never been partial to fighting games, so it's really no surpirse that this game didn't tickle my gaming bone one bit.
As the fighting game genre goes, this one appears to only have one really interesting thing going for it. Instant replay. Sure it's neat, but other than that, I'm really not very impressed.
The graphics might look better if you just left them as 3-d images instead of making them into "Flashed" sprites. The sounds effects are okay, but some background music would help a lot. The choice of several fighters and the playfield background is a nice addition, but I feel the time spent adding those options could have been better spent elsewhere. For instance, isn't kinda lame that I can beat my opponent by just holding duck and kick. Sizing up the game would be nice too. It's hard to really see what the heck is going on without dropping my monitor resolution drastically.
Anyway, I don't mean to rip on Stay Alive too much. I've never built a fighting game and I'm sure a lot of work went into building this. You obviously have some good Flash talent.