I've never played a game that felt like the designer was actively fighting you as much as Rimworld. It feels like it was designed by your childhood friend that always had to use their everything proof shield. It just feels like the game immediately counters whatever you do. You want to defend yourself from wild animals and raiders so you build a wall around your base. Great the animals stay out, but the raiders each punch an individual hole in the wall when they come and attack you from every side. Now you build a killbox filled with turrets and traps with an open door so the raiders will walk through, but the game sends you sappers that break through your wall at an undefended spot in seconds and charge from your undefended flank because raiders avoid turrets making them useless. So you make your wall 5 thick and mount turrets absolutely everywhere, but the game sends drop pod raids that bypass everything and drop through your ceiling. So you build a base inside a mountain so raiders can't drop on you, except now you have bugs flooding directly into your bedrooms smashing up all your masterwork furniture. I get that the game needs to adapt to continue challenging the player, but it just feels so artificial, like it's peeking at your cards before deciding what to play. Building good defenses feels so metagamey, like you need to exploit the AI or just get trashed. Like the fact that you need to leave an open door for raiders or they'll just destroy your granite walls in seconds is so counter-intuitive it feels unfair.
The fact that raids scale off of colony wealth and the game doesn't give you any advance warning are also major problems. It almost feels like the game is setting a trap for the player. You handily fend off the first couple raids consisting of a couple guys sharing a pointed stick, so you gain a false confidence and focus your energy on the ever pressing needs of keeping your colonists happy, fed, and occupied. You can get so lost in building up your colony that it never feels more important to redesign you defenses until you have 63 militors punching 63 individual holes in you walls because your alpacas have bred out of control and you smoothed all of your walls and floors. There really should really be some sort of indicator of "the next raid will be in about this many days, and will be around this big" to keep raids in your mind amid the moment to moment gameplay and keep you from being totally blindsided by difficulty spikes. Frankly raids (and especially mechanoid ships and clusters) never feel like a fun challenge, they feel like a chore that the game punishes you with for playing and to stop you from progressing too quickly. I have almost nothing to gain from a raid and everything to lose when the leader of my colony, a high level psycaster with many useful abilities, the only one with decent social skills, and wearing prestige cataphract armor with a samurai helmet, might get her brain exploded by the FIRST shot fired in a combat with lancer (yes, I reloaded. This is why I always save at the start of a raid. There is enough time spent fast forwarding without needing to spend hours training up new colonists from scratch).
While I'm ranting, I might as well mention this. Hauling sucks! I can't believe this hasn't been fixed yet. I can live with the stack sizes being small, and only being able to haul one stack at a time even though they can carry 10x that much in a caravan, but good god, get your priorities straight! Crops shouldn't be rotting in the fields because my hauler is dragging 10 corn from my freezer to my kitchen all day long. Haul spoiling, then deteriorating, then anything else. Give me a selector to designate priority haul. I know there's mods that fix this. This should be vanilla. Hauling is the single most tedious and micromanagey aspect of the game.