* Catnip production varies by season. Winter is harsh. Your kittens can starve to death.
* Kittens gain experience the longer they stay on a specific production type. This improves their efficiency. A single master level kitten is worth 1.1875 unskilled kittens. But, whichever skill is being slowly gained because a kitten is assigned to it, all other skills are slowly
lost while the kitten is not assigned to them. So you'll benefit from generally keeping kittens on the same task, and not letting them die.
* "Just build everything" is not always a good strategy here.
* 5 ticks per second. By default the game shows you numbers based on seconds, not ticks. If something reports 0.00/second, it's probably positive per tick, but not enough to equal .01 per second. You can adjust than in settings.
* The game has multiple persistent upgrade resources and systems. But don't be surprised if you don't see any of them in your first week of gameplay. There's some dispute as to the best time to do a first reset, but the significant early game marks are "once you reach 35 kittens" "once you reach 71 kittens" and "when you unlock concrete huts." 35 kittens makes you eligible to receive karma, which gives a happiness bonus that increases kitten production rates. 70 makes you eligible for paragon, which increases all production rates plus can be spent on upgrades. And concrete huts, once unlocked, allow you to relatively quickly increase your kitten population by a lot. In each case, you'll probably benefit from not immediately resetting once reaching one of these points, but rather getting at least several more kittens to actually benefit from the thing you'e unlocked. For example, if you reset with 35 kittens you're "eligible" to receive karma, but the actual karma you'll receive will be a very small decimal. If you push to 40, that's the point you'll get a full point of karma worth a 10% happiness bonus. Same with paragon, where each kitten after 70 gives one point. So resetting at 71 gives you only one paragon, whereas pushing for even one more gives twice as much. Some people on reddit claim that 120 is a good first reset point, but personally my first reset was in the low 60s, and I don't regret it. Things really start to slow down after a certain point. But if I were to do it again, I'd consider pushing to 75-80 for a first reset, to get at least a couple points of paragon too. But I wouldn't stress over it too much. The 30% happiness bonus I received from karma from that first reset definitely helped on my next run.
*
wiki