I think maybe the way to spice up the first two stages is to add one or two more enemy types? The first stage has a lot of popcorn enemies, and the second stage has that long bit with the boxes, bombs, and crabs. Just a thought. I think when you consider the entire levels they're pretty dynamic, though. And I think the difficulty of the stages is just great. I really have to use the continues in this game; I like that even the first level brings it.
Also, I am gonna straight up smack you in the face right now: DO NOT BE DOWN ON YOURSELF FOR THE ARTWORK. Are you kidding me? The artwork in this game is absolutely amazing. It's fucking perfect. Don't think for a second
that you need a "proper" artist, because the art of Final Boss totally nails it. Just 100%. I'm not sure I like the artwork of *any* shooting game more than Final Boss's. If Final Boss is going to stop being "some indie freeware shooter" (I think it's much more than that already, honestly), then it's going to be because the game has 6 levels, a caravan mode, online leaderboards, native joystick support, achievements, etc. That's up for you to decide. But it will be worthy of someone's $10* because it's a well-rounded, feature-rich game, and NOT
because you changed your artstyle. If you hire some "proper artist," I will cry. I'm no proper artist myself, but I understand art on some fundamental level at least (source: http://specialworld.tumblr.com/
), and I can tell you that Final Boss is pure gold. It's chunky and authentic, and it doesn't seem slavishly retro like so many other indie games. I will not let you tell yourself that the art in Final Boss isn't good.
As for the color scheme, I myself quite like it. I think it's stylish and will really appeal to critics. But I can understand if somebody played the game and thought, "Hmm, this is kinda basic, isn't it." So maybe (one day) as unlockables you should make one or two color filters. Experiment with coloring the game in full. Or, try to make each level a different contrasting color scheme. I dunno. Experiment with it. See what works best. But don't go thinking that your color scheme is "worse" because it's more basic. Try things out and go with your gut, and if you think you have a couple viable options, include them in the game as unlocks.
* I say $10 not because I think a completed Final Boss game will "only be worth $10" but because I understand the realities of the situation. I think if you do a really good job and play your cards right, Final Boss could easily make for a solid $20 download, which is pretty much as high as people will go for a download-only game. But as a new developer you're untested, and as a traditional scrolling shooter dev you're really working against popular opinion. At $10 or $15 you're still working within the "somewhat inexpensive" game range, but you're also assigning yourself a somewhat premium price for a download game. What this does is it adds value to your product. A ton of people will balk at paying $40, $60, $80 for a scrolling shooter, but at $10-$15 they can be convinced by a good review. And by paying a little bit more than $1 or $5, they value your product a little more, and they'll treat it as an actual game rather than something they play on a boring Friday and forget about. Because Final Boss is a game that really just gets better—I think it would be a travesty for somebody to game over on the first stage and say "that's it?" But if they only pay a dollar or two, they'll treat it as expendable and they won't play any more than that. They'll game over once and never play it again because hell, what's $2? I don't wanna wig you guys out or anything, but I'm telling you straight up—you are making a gem. And not just from "super shooting game fan" perspective. Final Boss has the foundations to be a game that anyone can play and enjoy on their own respective level. Final Boss really cuts through a lot of the bullshit that makes people hate shooting games.