You did good.
With Genesis, you had a pretty solid game. This one, however, I think needs to be tweaked just a bit. I admit, you've got a great start here, it's just that a lot of things need just a little tweaking.
The items, nice. The map, cool. Negative colors when they get hit, awesome (hey, can I get that from you?).
The movement, however was a little shaky and I found myself not getting stuck but getting in weird places when I hit the wall in just the right (or wrong) way. And during the escape sequence, I died just by going down where i was supposed to. The second time, though, it worked perfectly.
The firing seemed to be a little off too, maybe it just seemed like it moved a little too fast...
The gradient backgrounds were allright, but they probably could have used a little more work since they didn't scroll or anything.
All in all, good job on the game itself and on your experiment in a different direction. I enjoyed playing it, some rough edges just need to be smoothed over. :)