Yo. Sentrigan here.
Below is a few random thoughts I wish I had access to before starting development. Maybe they'll help you? I hope you enjoy my ramblings anyways.
DON'T MESS WITH RESOLUTION (MAINLY FULLSCREEN)
It's a nightmare. Doing resolution stuff is the least fun. I can't NOT recommend it enough.
Try to keep it really simple. As of the time I'm writing this, the most common resolution is 1920x1080 (16:9). If I knew before what I know now, I would have just divided those numbers by 3 or 4 and scale up from there. Pixels getting stretched and squashed is just... no. I'm still mad about it, and I haven't touched any resolution code in 8 months.
Some games choose to have imperfect scaling (Nuclear Throne for example, has extra columns of pixels, but the art hides that really well!), others to extend the playing area (Risk of Rain does this, and it looks pretty ridiculous as high resolutions...), some are smart and work off common resolutions (Wizorb does this, but weird resolutions still have imperfect scaling), and some just don't even bother (Try to find a Wanderlust:Rebirth screenshot that doesn't look chewed up by dogs)
NEUTRON STAR has the advantage of not having a moving camera, so it solves this problem by changing the size of the camera to scale perfectly to fullscreen. The base size is 320x240(4:3), so if it needed to scale up to 1920x1080(16:9), the view would change to (roughly) 288x216(4:3), and fill the rest with black bars. HOWEVER! I would seriously recommend against this. It makes working with GUI layers a huge pain. You do get perfect scaling every time, though.
PLAN EVERYTHING BEFORE EVEN STARTING ANYTHING
This one is kind of a given, but I learned it the hard way. I have about 2 or 3 folders of random thought-vomit as I iterated through solutions to possible problems, but it wasn't always the case. Early on I wasn't terribly sure of where I wanted to go with the game, so it was a mostly trial-and-error process.
This results in early code being awful. I've had to rewrite a lot of the stuff made early, mostly because it was impossible to work with. Also, having things planned out from the start (not just solutions to problems, I mean the entire game) is a major motivator. I'd love to say my work ethic is impeccable, but when you don't know what to do next, you waste a lot of time bumbling about.
There was a month in which I was basically 100% isolated from other human beings. Friends were busy with work, I didn't have school anymore and wasn't in college yet, and I don't really have any online friends. So all I could do is work on the game all day then go to sleep.
If you play games, you've probably done this before. Wake, play, sleep, repeat. The end result being, after 2 or 3 weeks you get extremely burned out, and you never play that game again. This happened to me too! Thankfully I was able to ease into development again, but you should pace yourself.
VISUALS ARE AS IMPORTANT AS MECHANICS AND VICEVERSA
I know this is a divisive subject, so I'll try to be clear. A game has to look good. This isn't about graphics, but rather aesthetic standards. Uncharted 4 is a good looking game, but so is Megaman 1!
Now look at something like Apotheon. Its a beautiful game, with a very unique (and well made) aesthetic. Its also one of the least fun games I've ever played. You float around the screen, graphics are unclear in a mechanical sense ("Is that a platform? Guess I- oh I died."). Old games were particularly guilty of this, and I'll fight anyone who tells me Donkey Kong Country is a good game for this very reason.
DO NOT EVEN TRY TO GIVE A DATE
I tried my hardest to release before 2017, but things just didn't pan out that way. Then I started college, so I didn't have time anymore, and so I could only dev on weekends, and so on.
What I'm trying to say is: You hold no power over the future. If you can give "when its done" as a release date, you probably should. Look at Valve's "valve time" or Riot's "soon(tm)". If a huge company can't give a reasonable answer, can you?
This next one is very personal, so feel free to disagree.
If you're mainly a programmer (I am), you're very aware of "programmer art". Thankfully, with blood, sweat and tears you can struggle for long enough to understand just a little bit of color theory and make something that looks decent. Music is absolutely not the case.
I spent around a month trying to make one song that wouldn't cause seizures and blind rage when heard, and I came up empty handed. Music is just outside of my realm, and from what I've read, I'm not the only one.
Videos are really painful to work through too. Twitter (any social thing, really) is a chore too, I probably spend 20 minutes looking at the screen before hitting send, just thinking about the consecuences of tweeting "check this out!!" with some funny bug.
Overall, I'd really like to stay as a one-person team. But if it means not having to suffer through that again? Not so sure then. I guess there's always publishers?
I can honestly write a lot more about lessons learned, but I've been writing for about 2hs, and just want to take a break. Maybe some other time I'll continue, or maybe it'll be lost forever to time.
If you want to talk to me, you can find me on twitter (@neutronstargame), or discord. Also, please vote for the game on greenlight, after you've checked out the game (check the bottom of the page for the demo!)