Well, I have two good reasons why this game is 50 fps instead of 60.
1. A lot of people still have old pcs and use outdated graphic-cards. When they see retro-platformers like this, they think it will run on old computers and then it runs shitty and they come to me and complain. But because this game is using lots and lots of graphics with alpha channels and shaders (blood, light, hell fog, rain etc), you need a decent graphic-card to run the game fine or else those alpha effects will make the game run choppy. This isn't noticable as much if the game already runs only at 50 fps, because a drop from 60 to 40 is more noticable than a drop from only 50 to 40.
2. The standard for the program I was using to make GunGirl 2 is set to 50 fps. I didn't even care about fps until maybe halfway through the development-time. By then, I changed it to 60 just to see how much stuff I would have to fix to make it run at 60 instead of 50. But it was literally EVERYTHING! Almost every timer in the game, rather it be timers for animations or timers for monster behavior, are calculated with a base of 50 = 1 sec. So this meant I would have to change everything I've done so far, every sound, animation, jumping, running etc etc, everything would have to be changed so it matches the new fps rate. And because I'm lazy as hell and I didn't want to spend so much time on something that has so little effect on the gameplay - I just changed it back to 50 and went on to something more important
