Yes, don't worry tilesets are free to use. I even like the way you used tiles, just I can't help you with making more. Problem is that if you'll later try to sell the game this won't work out, you need one style everywhere. Try searching for people interested in your project, some artist might pick it up as rev-share project and redo everything for every level.
From the old video you posted, I suggest you work also on visual feedback details. Like knockbacks, screenshakes, maybe make it more fast, rather than it being like early Metroid slow paced. From new game standards games tend to be faster. With a bit more flow and some simple story idea. Maybe some new mechanics that could be used for level progression like the roll POWER, just something new you have to get to progress deeper. More level branching leading to some dead ends maybe and some collectables for some sort of reward.
Hey! I'm just wondering how old are you and how well you know programming. I'm now looking at your game, seems nice, just people don't dig much into these type games anymore and I doubt it will be successful financially . Currently I could work on another rev-share project with someone if you are interested, it would be visually better game.
I am an experienced programmer and have made games both for 8-bit consoles & and the Jaguar 64-bit console. Asteroite has received quite a lot of attention in the Jaguar community. I have also made a roguelike RPG for the Jaguar:
I started making retro inspired PC games long ago, but it's hard to stand out in such a crowded market. E.g. there are so many other games being released for it. For the Jaguar, my previous games has sold enough for publishers to be interested in publishing my games.
I really like your art style and I am quite sure it will be highly appreciated by the people who buy my games. Definately I am interesting in working with you, I have several ideas. I am also interested in hearing about your ideas. The Jaguar has more power to produce even better looking games than these, provided there is an artist to support it. I also started looking into making 3D games for the Jaguar. Is there a way I can contact you privately? You can send me a PM on the AtariAge forum, my username is phoboz.