For this playthrough I use the Sandbox mode.
Reasons:
- my favorite tech tree mods don’t work.
I can’t stand the stock tech tree. Kernels develop solid rocket boosters before they have wheels, ladders, wings, or flat concrete runways. Also: the nodes are wired and many molded parts don’t have a good place in the stock tree. - Career mode (also science mode, kind of) does a few things I used to enjoy but don’t enjoy these days
- money grinding. I do enjoy coming up with cheap concepts tailored to contracts so I can farm money. But it gets repetitive. Many times it is just waiting for an easily formally contract and that’s it.
- contracts sometimes break immersion. I have made my first orbital flight and get a contract to rescue some dude stranded on Minmus.
- science grinding. I figured out that you can grind the Kerbin SOI to get all the science to unlock the whole tech tree. I do it. I just need to, my OCD tells me I am missing out otherwise. Test all the instrument in all biomes of Kerbin at all altitudes plus do all the EVAs flying, landed, and so on. Easily grindable but not fun. The KSC alone has four biomes or so.
- station building and maintaining isn’t encouraged. But I like that. In career mode it is a waste of money.
- I like planes and SSTOs and reusable rockets. In career mode those are almost never worth it. That might be realistic but it isn’t fun.
- …I had another point but forgot it. I’ll edit it in later.
EDIT: remembered it. It is a weird effect. Once I am advanced so far into the career that I can do the stuff I really want to try out, I have unlocked all the tech tree nodes so I don’t get meaningful rewards/incentives anymore. And/or I have a ridiculous amount of money making the game quite similar to a sandbox game actually. And/or I run out of motivation or the next version of the game is ready, which causes me to switch and abandon my (usually heavily modded) campaign because I would need to wait for all my mods to get updated.
And of course I know that I tend to install mods that make the game a lot harder, which makes progress even slower. That’s not great for campaigns somehow.