For unused content, see: Unused Featuresdevelopment roadmap.
NOTE: This is not a list of features that weren't implemented, this is a list of upcoming features.
v1.3.1 - The Optimized Update
The Optimized Update is designed to improve overall performance of Slime Rancher. Yes, even though we're nearly 3 years out from initial release, we're still hard at work to make Slime Rancher the best possible experience for everyone!
We'll be upgrading Slime Rancher to Unity 2018 to take advantage of numerous performance improvements. In particular, performance on Xbox One should be noticeably improved.
Drones will be receiving a few improvements to give more options for free ranging ranchers, deliver to refineries, and feed fire slimes effectively.
Our French translation will be receiving a complete overhaul and we'll also be adding an official Korean translation!
There's a slew of other small fixes and optimizations we'll be packing in to 1.3.1 that while small on their own, should add up to a better experience.
Slime Rancher: VR Playground
A VR Playground will be released on Steam as free DLC for Slime Rancher in the fall of 2018! The VR Playground allows you to experience a little bit of Slime Rancher, hang out with slimes, or just sit in the flowers and relax.
Viktor's Experimental Update (1.4.0)
Join Viktor Humphries and test a virtual simulation of the Far, Far Range. Well, a work-in-progress version anyway. You see, his work is hitting a wall because of the numerous bugs in the code as well as an unusual phenomenon: glitches that take the form of... slimes? In any case, help him sort the issue out and you'll be rewarded with some nice upgrades and even a new ranch expansion!
Glitch slimes have been discovered living inside Viktor's Slime-ulations and it's up to you to help him quarantine them before they spread! But like any bug, glitch slimes can be tricky to find: they are often hiding in plain side[sic], pretending to be objects or other slimes in the virtual Far, Far Range. You'll need a keen eye and a full tank of Viktor's patented debug spray to get the job done!
It wouldn't be a very science-y update without new slime science gadgets, and Viktor's update will include a chicken cloner, deluxe drones, and more!
Other New Things
Viktor's Experimental Update is shaping up to be a pretty big update and there's even more packed into it that we won't reveal until later.
As of version 1.1.0, Boom slime explosions and butt-stomps no longer displace Echoes. However, Monomi Park has mentioned that this bug might be re-implemented in a more formal manner in a future update.
More achievements are set to be released in late 2018. 
- ↑ http://forums.monomipark.com/viewtopic.php?f=10&t=5538 - "Fixed bug where boom slime booms would push echoes out of place. However, having seen the amazing fireworks displays some players created, we’re committed to remaking that awesome discovery in a future update in a more formal capacity."
- ↑ https://twitter.com/monomipark/status/966110908358451200