Yeah, I played the game for about 6 hours straight when I bought it the other day, and unfortunately I'm already running out of stuff to do aside from achievements and self-imposed challenges. It feels like perhaps the game is a bit too open at the moment, allowing you to get good stuff early on. Tarr infestations were never really a problem since I didn't have to research high walls or air nets etc. they were just available as long as I had the money for it, and they required no maintenance at all. Not only that, there really isn't slime 'breeding' per-se, but there is slime... combining, I guess? Which is fair, the game isn't called 'slime breeder' or anything.
Some new types of corrals would be nice too, or upgrades. For instance, I kinda want to merge the four corrals at the start into one super-corral for all my honey/blast largos. The Range Exchange is also pretty lackluster, rarely giving you anything worthwhile as far as I can tell and often times will just end up exploding a bunch of chickens across your farm.
On a final note it's fairly tedious to have to sprint your way across the map just to get to the next area. There are teleport pads to bring you back to the farm, but they are one-way trips. The ranch isn't in a centralized location with paths branching out into more prosperous/difficult locations, and instead you have one exit that leads you out into the world, while the other two paths lead to specialized ranches and the fourth leads to the ocean.
Still, that just means that it's a bit lacking for 20 bucks, right now. Perhaps after some more development time has been put in I'll come back and see what's been improved. I know while playing I've come across a lot of 'under construction' barriers that imply the world will be much less linear and more varied. Does anyone who's following the game know what pace the development is going?
I am currently making a cage filled with Tarrs, so whenever i need to get rid of random junk/unwanted slimes i just pitch them in the cage of death.
You could also just use the incinerator.