Certain objects in the zone can be interacted with, with each character having unique strands of dialouge for them. There are also specific NPC's that can be spoken to with fully voice acted lines. The lines also change after each boss fight, so if you like worldbuilding its worth it to talk to them.

After beating the first boss and unlocking the next district, you unlock the ability to take photos of various grafitis scattered around the city and use them to decorate your guitar case, the icon for the pause menu. All of the grafiti you gather are fanart submitted by people during the development of the Encore Edition. In order to gather them, you simply walk by with the camera panned to view the art, the image will flash slighty and a sound cue will play indicating the photo has been taken.

Another thing that unlocks is the ability to gather Mini Qwasas and Stickers. Mini Qwasas come in different forms, small tubes worth 1, larger groups worth 3, and large cubes worth 50. You can use Qwasas to power broken objects in each district, awarding you fans. Stickers can be stuck to your weapons to increase your stats, and there is a LARGE DIFFERENCE in how they work between the two versions. In the base game, stickers last for 3 boss fights, in the Encore Edition, however, they last indefnitely.

In your sewer headquarters, if you go down to the storage room after fighting a boss and there is a small icon of a chicken leg, you can feed Ellie, the aligator, and after feeding her 5 times you permanantly unlock fast travel.

If you have no stickers of a certain type in your inventory, that sticker will respawn throughout the city. Stickers placed onto weapons dont count when it tracks how many stickers you have, so you can gather 8 of one type of sticker simply by placing them onto your weapons and reloading the zone to respawn them.

There is a way to delete and create stickers by using the Build function. Say you have 1 health sticker and 8 sticker slots, by saving a build with that one sticker on, and then removing that sticker from your weapon, if you load the build it will CREATE a sticker instead of pulling from your inventory, duplicating it. This also ERASES whatever sticker was in that slot, so you can clear all of your stickers and then run through the district collecting everything again, netting you more than one of each sticker. You can use this to duplicate the invincibility sticker added in the Encore Edition, and they stack up to 99.