I like retro games, because I grew up in that era playing them. They bring back a lot of nostalgic memories for me. I like remakes of them to, if they are done well. But there are certain things I don't miss , and those are clunky controls, and confusing levels.
I never played this particular game before, and I can see you put a lot of work into it. The music, sound, and graphics, all seem well done, and they really fit the look of an old 8bit computer in the 80's. So well done on that.
However, I can't find myself liking the floaty and clunky controls. I understand you're in space, and there is low gravity, and all that, but it rarely works well in confined spaces, where precision is sometimes required. I understand from your description that the controls are a slight improvement from the original, but then, from the sounds of it, you also changed the level design. Whether that helped, or not, I can't really say. I just hate the jumps you have to make over the sliding platforms onto the blocks, and the jump you have to make at the end of level 2. I also dislike how you can't jump farther when turned backwards, or how it's a pain to jump off ladders.
The level design itself is not bad, but there are some very confusing aspects to it. It may not be entirely your fault, as I didn't read the instructions for the game, and forgot how some of these games worked back then. I spent a lot of time trying to precision jump over the slide platform onto the block, thinking that it was the only way to progress further into the game. It wasn't until a dozen attempts later, after hitting the slide and falling down into the screen with the "EXIT" sign, that I played around with it and found myself on the next level. Similarly, I found I could change guns on the gun sign, which I found out by dumb luck on the 2nd level. So, maybe you could point out what those signs are for in the opening screen with the control layout. That may help reduce confusion, because.... well, people are dumb, and I am part of that group who won't read instructions unless they are forced in front of them. I also like all the hidden levels in the game, though some of them are hard to get to.
In all, you did a great job in resurrecting this game from the past. But, the clunky controls, and the dated meanings behind the signs, may deter many players away from the game.