When I first got an ipad and tried to port Kompendium to it I ran into a lot of problems with controls. The games were designed around how they felt to play with buttons and my naive touch implementations didn't feel good at all. (The exception being of course Glitch Tank which turned out to actually be a better fit.) I had no experience with touchscreens before then, didn't have a smartphone or anything. So I'd no idea what I was doing (good place to be IMO, recommend visiting often).
Experimenting with different controls I found that with touch everyone seems to have different expectations. What one found completely natural would baffle another. Then they'd suggest how it should obviously (to them) work, which in turn a third person would find totally wrong. Of course it's absolute, of course it's relative, of course you have to put your finger where your ship is now, or where you want it to end up, of course it doesn't matter where you touch.
All this was complicated by having two players. Often someone would end up reaching across the screen and blocking their opponent - completely accidentally. If that happens on purpose that's pretty interesting to me, eventually I did make O which embraced it, but at the time I was working with existing games that didn't have this concept. Similarly if you design a game to have a really clear distance between my bits and yours (as in Shot Shot Shoot) then you're probably fine - some of the Kompendium games did already but others it didn't make sense for. I decided to start making a singleplayer game and get the controls right before dealing with the harder case of multiplayer. So I started Helix at a jam in 2012 as a simple exercise in control schemes.
Once I added some enemies to avoid, playing around I enjoyed weaving around them and skimming close more than just keeping away from them so I added a rule that encouraged doing this. Added a few different enemy types, lots of particles, toned down the awful strobing lights, and then it was mostly done but I got sidetracked making VESPER.5 and then a bunch of other games. For a long time it kept sitting there basically finished but with a few critical things needing to be done, boring technical things like rewriting code from the jam to actually run smoothly on an older ipod, and I was much less motivated to do that than to make a new game. Other people kept telling me I should hurry up and finish it but I was always off making some kind of weird cyber roguelike or something. And then when I did get around to doing anything on it I usually ended up doing something simple and fun like adding a new enemy type instead of the important things. So it somehow ended up taking a couple of years longer than it should have to get done. (I feel pretty strange about that, it doesn't seem like so long, years shouldn't be thrown around lightly.) But it did benefit some from its long maturation, in particular there's one enemy that took a year to come up with that to me is the one sublime element that lifts it from being just a simple action game to something worth having made, also how the powerups work took some time to settle and just the enemy patterns have been refined. Also spent a long time tuning the controls, getting them exactly right.
At one point I accidentally deleted it and hadn't backed it up so I had to use some kind of deleted file recovery tool to get it back. I'm still convinced it returned with glitches it hadn't had before..
Andrew Toups did the sound for it and it's perfect. Tim Rogers introduced us after I'd been discussing the design with him with reference to their game ZiGGURAT, which was one of my inspirations for how to do a solid small-scale action game (the other main one being of course Super Hexagon).
Anyway it's out now for ios-things.
Maybe now I can finally go back to the harder problem of making a multiplayer game with good touch controls?