Inspirations - A Love Letter to KSP

Welcome to Asteroid Defense, this is my working title for my indev game that attempts to make orbital mechanics fun and aproachable. I'm building this as a platform for telling some stories as well as a response to people who liked KSP but bounced off of it because "thinking with orbital mechanics" is harder than "thinking with portals".

A big part of my inspiration for this game was a mission I did in KSP. For context I have something like 800 hours in KSP, I'm also a bit of a curmudgeon when it comes to quality of life mods so I refused to use things like MecJeb. For example: I used a piece of cardboard as a protractor to figure out when to initiate Hohmann Transfer Orbits rather than a seperate calculator. I was literally holding it against my screen while in map mode.

All of that to say that I had a mission where I launched ship min maxed for science collection. This meant as many reusable science modules as possible, a single scientist Kerbal to reset them, EVA seat for flying rather than a proper command module, and a single nuclear engine with as much Liquid Fule as felt reasonable.

In this mission I managed to orbit the Mun, Minimus, Eve, Landed on Gilly, and then managed to get out to Jool.

On the way to Jool I knew I had just enough delta-v to be captured but it would be a highly eliptical orbit, one that would inevitably be disrupted by one of the moons. This forced me to learn how to use gravity assists. Using my the last of my fuel and 5-7 gravity assists I managed to circularize my orbit and eventually get into a stable polar orbit around Laythe.

During this mission I finally "got" it. I glimpsed how gravity can pull a ship's orbit. How you could pass in front of a planets path to bring your apoapsis down and pass behind to extend it. It was incredibly gratifying because it was true. KSP is a simulator, it uses some aproximations (Phased Conics) to make the world playable in real time, but the fundamentals are there the universe actually operates in the way I had glimpsed.

With this game I want to make that moment easier to obtain, in the hopes that some of my players go on to play KSP or make their own games with real orbital mechanics. Maybe one day, orbital mechanics will be as easily understood by the average gamer as platforming is.

In pursit of that goal I set some design constraints:

My game is in 2D. This honestly doesn't matter that much in terms of learning how orbits work. In the real world most astronomical bodies exist in a large plane we call the ecliptic. It's one of the reasons we theorize that the solar system started as a spining disk of gas. So by removing the Z axis you can still get to most planets and you reduce the amount of wrong inputs the player can do.
Designed for controllers. This was a later decision. If I want the widest possible audience I should design for the control system that is most ubiquitous. Hence the controller. This has also helped in limiting the scope of this project. In my first few passes I had a bunch of crazy keyboard combos to open menus and configure things, all of that was clutter getting in the way of learning how to navigate the world.
And even more "Toy" solar system than KSP, even more "Toy" than Outer Wilds honestly. This is the choice I've strugged the most with. I do think that in my games ACT 2 I might expand the size of all the planets. I've done some interesting things with coordinate translations to artificially increase the size of planets surfaces but it's clunky. I'd rather have a more realistic solar system but the first ACT is more of a long tutorial anyway.
Unlimited fuel. In universe the explanation is invisible supply ships that are constantly loading fuel into the player's ship not that I think most players actually will think too much about why they can just burn forever but I still needed a reason.
Finally, a stupid amount of thrust. This was initially tuned to be similar to the thrusts of the ships in the Expanse books and tv shows but I've since moved towards a thrust that feels good.

So yeah that's the game loop, some thoughs on my design choices, and some hints about my future plans with this project.

Good luck out there Pilots. I look forward to seeing someone beat the boss at wave 50.

-- Max

2026-10-15