Good points! Maybe I could have made the cursor change depending on the fire mode... Although I do kind of like that uncertainty aspect of it too, needing to track which mode you are currently on, leaning into the whole one button having two functions which in this case are opposite functions. I think I could definitely have made the teleport mode look more drastically different from the zap mode though. A larger field that goes around the glass coil instead of forming inside it would have been a lot more readable. Glad the switch did it's job there!
I heard there was some difficulty distinguishing the humans and robots in a quick playtest, so I went back in to do a fix before release, unfortunately for f.lux users and the like, the main gist of that fix was to tint the robots faces blue instead of orange, which is more or less the opposite of what blue-light filtering programs do!.. Something I didn't really think about when I made the change... I wanted to keep some difficulty there, but I could have definitely gone way harsher and use dark greys instead of just using light-blue. I guess you're getting something closer to the original sprite experience that way XD.
Yeah, I had some code in to increase the spawn speed as the waves went on, but I don't know if there was a bug associated with it, or the ramp up was just too gradual to be obvious. In any case, the trains shoud at least return quicker as the game goes on. I'm glad I set the minumum wave duration to 60 seconds, or there would have been more waiting for them to pull in, maybe I could have added even more time, or variation on the time in that direction.
You're absolutely right that there's a fair amount of waiting, especially at the beginning. I can think of a few things I could have done code wise to optimize that, but in part I quite liked that it gives players a chance to see the background, which you mosty ignore during play. It might be a good idea to drop out some of the background elements - conceptually tilt the camera down toward the ground a bit, to fit more trains on screen at a time to help bring the difficulty up.
Thanks for the comments!