Unfortunately, there isn't a magic formula That's likely exactly what you'll have to do to get good balance... play it over, and over again.... then play it another million times... then give it to beta testers or friends to play, gather feedback, and re-adjust... and it probably still won't be completed... Balancing is actually quite a skill imo, and the better you become at it, the better you'll be able to make extrapolations about the gameplay systems - and be correct... making it easier to do. But it will always be a long, often tedious process...
Excellent points. The only thing I would add is make sure you start off slow and easy. You don't want to overwhelm the player. Then just gradually ramp up the challenge until you reach something you're happy with. So just start with something simple and build from there.
Just don't make it too slow and easy. We've been collecting data from Terminal Escape, and only about 3% of people make it to the second terminal (which starts at level 16 out of 60). We are working on an update to try to fix that, but we think there are two things at play here: - The first is that the game starts out slow and easy, and basically the entire first terminal is slow and easy for a seasoned gamer. It starts to get really challenging after that with the third and fourth terminals being really intense, but people lose interest before getting there. - The game isn't selling too well so most downloads are from the cracked version. People are more likely to stay with it if they paid for it.
Increasing things exponentially is usually a good idea. I did something similar in a game to increase how powerful weapons are: power_at_level = initial_power * 1.5 ^ level So each additional level the weapon is 1.5 times as powerful. I found that to be a good rate. It still gave noticeable increases level over level, but kept the rate fairly manageable. Then I had an equation for determining the "power" of weapons that took into account things like firing rate, bullets per shot, damage per bullet, etc. This way I could compare different weapon types (machine gun vs spread gun vs missiles vs laser) and assign each one a power rating, which is important to balance all of them against each other and as they increase level by level.