This is an amazing game, but I have some suggestions.

[ThunderstruckHR]

WARNING! WALL OF TEXT INCOMING
Title says it all.

The slime design is amazing, the maps are fun to explore, and the items and updates always keep me excited for the future. I really hope you guys continue to make this game better and better, and reach the point of not just being early access. Although there are all these pluses, I have a few downsides and suggestions...

Collisions.
I'm not sure what engine you guys made Slime Rancher on, but the collision with the walls is pretty bad, honestly. I constantly find myself getting stuck on a hill when I'm using the jetpack, and when I ram into a slime by accident (or purpose lol) occasionally I'll end up on top of the Slime for a second, then fall off, then get back on again until I jump off of the Slime. If you guys could help with that, I think this game would be much easier for a lot of people.
Feedback.
Although the developers spend a lot of time working on the game and such, I think they should interact with the crowd more. I play a lot of Overwatch, and one of the reasons I love their developers is because they interact with their fanbase on the forums so much, it's amazing. I've seen numerous posts on their forum pointing out a bug, and the head developer will chime in to tell them "Hey, we're fixing this internally, it should be live soon. Sorry about that," and it's amazing. So Monomi Park, If I were to suggest anything, it would be to get on forums more often and interact with us, and possibly update the UI? It looks kind of odd honestly.
The jetpack is a huge issue.
I think the jetpack needs a huge nerf. I have, in numerous occasions, been able to travel to areas without a key, just with the jetpack. I'm not sure if it's a feature or not, but I still think that the boundaries for where you can go with it should be changed somehow.
Slime Keys.
These guys are a really fun addition to the game, but I often times feel that they shouldn't be the only way to get Slime Keys. It gets really boring really fast when I constantly have to scour the whole map for a bunch of chickens or vegetables, and only to get a key that unlocks an area that I could already get to by jetpack. I think quests would be a great way to solve this issue, for instance, "A large pack of Tarrs have been found near Coral Reef, and they're terrorizing the nearby slimes! Kill them off and keep them away from the Slimes through the nightfor a Slime Key as a reward!" Something along the lines of that would be more interesting and fun than shooting 65 fruits at a big blob.

That's about all I have to say, sorry about the long post, and I hope you guys take note.
Thanks!

[BeatrixLeBeau]

To do this they would have to rework the engine, but this may actually happen, as the game is still being developed.

Overwatch's team is huge, allowing for devs to have an abundance of spare time, slime ranchers team spends most of their time on the game, and if they did reply to most of the forum posts, it would take longer for more content to come out.

This is a real problem, but it might be intentional, slime rancher is a very open world game, not using ant invisible walls, but if it did need to be fixed, they would have to spend time placing new entities at the problem zone.

We do need new ways of getting keys, like solving a puzzle at the ruins, or trading a certain amount of various Plorts.

[EmeraldPlay]

My opinions on this:
The collision thing wasn't really an issue as I recall until around 0.3.0 when they changed it to what it is now.
I would like that too, but devs probably don't have much spare time, and there's only 5 of them at the moment (with a 6th dev coming soon). Also, the UI can't be changed much I think.
The jetpack "issue" is intended, and the shortcuts you make are just you being clever. But don't you think that it's more convenient when you unlock the doors to go through them?
The ways of getting slime keys is fine, it doesn't need to be changed.