One of the biggest games of the year is embracing seasonal events to get players excited all over again.

Pokémon Go is back on top of the iPhone top-grossing charts in the United States after falling as low No. 10 last week, according to market intelligence firm Sensor Tower. Developer Niantic updated the location-based augmented reality app that puts digital monsters into the real world with you using your smartphone’s camera earlier this week to celebrate Halloween. It now awards players with more candy to upgrade their collectible creatures, and more ghosts and other spooky Pokémon are out on the streets than usual.

Pokémon Go Halloween began Tuesday, and it will run through the first day of November. And it is one of the key reasons the game is back at the top of the $36.6 billion mobile gaming business.

Pikachu is back!

What’s notable about the Halloween event is that it doesn’t include any new content. Instead, Niantic was able to engage lapsed fans with a simple remix of resources that are already inside of Pokémon Go. This suggests that the company could continue doing events like these without having to invest heavily in building totally fresh content. And when Niantic does introduce new monsters and assets, it should have an even bigger effect than this week’s event.

Pokémon Go was also the top-grossing mobile game worldwide in September, according to a report from SuperData Research. That ranking is in jeopardy if it continues to fall behind games like Mobile Strike and Game of War, but it is still making quite a lot of money as long as it’s in the top 10.