Hitting the Right Notes: How to Play Custom Songs and Charts in Project SEKAI

If you spend any time scrolling through TikTok, YouTube, or X (formerly Twitter), you’ve probably stumbled upon jaw-dropping rhythm game clips of Project SEKAI: Colorful Stage! featuring tracks that aren’t actually in the official game. From viral indie VOCALOID hits to impossibly fast meme charts, the community’s creativity knows no bounds.

If you are wondering, “How do people get those custom songs and play those custom charts?” you aren’t alone. While the official Project SEKAI application doesn’t feature a built-in custom song importer, the community has built an ingenious ecosystem to let players enjoy fan-made charts.

This comprehensive guide breaks down how the community plays custom Project SEKAI content, what tools you need, and how you can dive into custom charting yourself.

The Secret Behind Custom Charts: Enter Sonolus

When you see creators playing custom Project SEKAI charts with authentic UI, slide notes, and flick mechanics, they usually aren’t modifying the official app. Instead, they are using Sonolus.

Sonolus is a powerful, open-source audio-driven game engine designed specifically to replicate the gameplay feel of popular rhythm games—including Project SEKAI (often running under skin/engine setups like Sekai Viewer or specific community servers).