Sandbox allows for truly ridiculous designs - the sort of insane, utterly impractical rockets I built just to see how far I could push Kerbal’s physics. When I'd get to a point in Career where I was having trouble progressing and started to get frustrated, I'd switch to Sandbox and build to my heart's content.

Without the goals of Career mode, I'd rather be playing Sandbox, where everything is unlocked and my imagination is the only limit. It retains the tech tree progression of Career mode, but removes other restrictions so the stakes aren't as high. Striking the perfect balance between thrust, weight, and fuel with only the parts and funds unlocked in Career mode made me feel like a brilliant rocket scientist. A heavier ship needs more thrust to go higher, which requires more engines. Bigger engines require more fuel, which make the ship heavier. Going higher requires more thrust, which requires bigger engines. Balancing funding, scientific progression, and reputation forced me to put thought into each launch, and the limited selection of spaceship parts made me think hard about how I could get the most from each rocket engine, fuel supply, or science module. All the challenges that come with actually blasting an object into space come into play.

I spent the majority of my time in Career mode. It's a lovely feedback loop that I can't get enough of. Every success (such as reaching a new record altitude) is really just a place to start over, only with better stuff. Through hours of trial and error, I finally came to a design and flight technique that did what I wanted it to, and it was fantastically satisfying because each accomplishment is just a step toward bigger and better things. In its Career and Science modes, Kerbal Space Program creates an incredible sense of accomplishment with each successful feat of rocketry.

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