Super Animal Royale may look like your standard battle royale at first, but it has quite a bit of side content you can find on its large island. One of the hidden story milestones has you put an end to a supposed rat before he can narc on whoever. Here is how to complete the Dart the (Not a) Rat Story Milestone in Super Animal Royale.
Before you drop into the match, make sure you are situated near Superite Mountain in the C3 section of the map.
Before you can do anything with this, you need to find a Dart Gun somewhere. There is no guarantee that you will ever find one, so your ability to complete this story milestone will come down to chance. Try to find Rebel Caches to open for an opportunity for one to drop, but again, there is no guarantee.
When you get a Dart Gun, go to C3, and enter the mountain. This area is quite broad and has a lot of items in it. Be careful of any enemies in the area and find the rat in the jail cell near the center of the mountain. When you get close, he will squeal that he is not a rat. Shoot him with the Dart Gun, and he will be poisoned and die.
You will then receive a notification in the top left of the screen that you completed the milestone and can redeem a new prison uniform cosmetic in the Milestone tab in the menus. If the rat is already dead, you will need to attempt this in a different match.