The primary function is to disable player death upon hitting obstacles.

You can easily pass through difficult demon levels.

Practice Mode places automatic or manual checkpoints throughout the level. This allows you to practice difficult transitions repeatedly without restarting from the very beginning.

If you play on PC, tools like Geode offer an open-source, safe, and community-verified modding framework. It allows you to download hitboxes and practice tools directly through a secure interface without downloading sketchy executable files.

: Allows you to see the exact physical boundaries of spikes and blocks, which are often different from their visual appearance. How to Use Noclip Effectively