Well...
As far as I can tell- I've played the original game before, and the game you provide is basically a dead-on Flash conversion, small graphical layering errors aside in some of the text. Nothing seems to have changed, and aside from some minor slowdown issues, the game runs EXACTLY as it would in MAME or what-have-you. Obviously, this took quite some talent and skill to do, especially if you had to reprogram the engine from scratch.
Buuuuut the thing is, well... For all your technical skill, the game itself just isn't that interesting, and it's definitely a game that needed a LOT of sprucing up in the first place. It's incredibly dull, repetitive, and you are swarmed by such huge numbers of enemies that your special attack is really the only option you have for getting out of most situations with the least overall health loss (and this ends up making Mark the most useful character without question, and Glen completely useless). All of these were problems pre-port, and it would have been nice to see some of these issues addressed.
I really want to give this game a ten based on the incredible porting job alone- you've even got the game's music in!- but I'm sorry. The game itself... seriously, you could have picked better, or done more with what you had.
Don't let me discourage you, though. If you want to take another shot at doing something like this game and want to stick with Video System's stuff, may I suggest "Spinal Breakers"? Fun shooter, that! =3
